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What is 70/51 - 2/7?

What is 70/51 - 2/7?

Here's how to subtract 2/7 from 70/51:

70
51
2
7

Step 1

We can't subtract two fractions with different denominators. So you need to get a common denominator. To do this, you'll multiply the denominators times each other... but the numerators have to change, too. They get multiplied by the other term's denominator.

So we multiply 70 by 7, and get 490.

Then we multiply 2 by 51, and get 102.

Next we give both terms new denominators -- 51 × 7 = 357.

So now our fractions look like this:

490
357
102
357

Step 2

Since our denominators match, we can subtract the numerators.

490 − 102 = 388

So the answer is:

388
357

Step 3

Last of all, we need to simplify the fraction, if possible. Can it be reduced to a simpler fraction?

To find out, we try dividing it by 2...

Nope! So now we try the next greatest prime number, 3...

Nope! So now we try the next greatest prime number, 5...

Nope! So now we try the next greatest prime number, 7...

Nope! So now we try the next greatest prime number, 11...

Nope! So now we try the next greatest prime number, 13...

Nope! So now we try the next greatest prime number, 17...

Nope! So now we try the next greatest prime number, 19...

Nope! So now we try the next greatest prime number, 23...

Nope! So now we try the next greatest prime number, 29...

Nope! So now we try the next greatest prime number, 31...

Nope! So now we try the next greatest prime number, 37...

Nope! So now we try the next greatest prime number, 41...

Nope! So now we try the next greatest prime number, 43...

Nope! So now we try the next greatest prime number, 47...

Nope! So now we try the next greatest prime number, 53...

Nope! So now we try the next greatest prime number, 59...

Nope! So now we try the next greatest prime number, 61...

Nope! So now we try the next greatest prime number, 67...

Nope! So now we try the next greatest prime number, 71...

Nope! So now we try the next greatest prime number, 73...

Nope! So now we try the next greatest prime number, 79...

Nope! So now we try the next greatest prime number, 83...

Nope! So now we try the next greatest prime number, 89...

Nope! So now we try the next greatest prime number, 97...

Nope! So now we try the next greatest prime number, 101...

Nope! So now we try the next greatest prime number, 103...

Nope! So now we try the next greatest prime number, 107...

Nope! So now we try the next greatest prime number, 109...

Nope! So now we try the next greatest prime number, 113...

Nope! So now we try the next greatest prime number, 127...

Nope! So now we try the next greatest prime number, 131...

Nope! So now we try the next greatest prime number, 137...

Nope! So now we try the next greatest prime number, 139...

Nope! So now we try the next greatest prime number, 149...

Nope! So now we try the next greatest prime number, 151...

Nope! So now we try the next greatest prime number, 157...

Nope! So now we try the next greatest prime number, 163...

Nope! So now we try the next greatest prime number, 167...

Nope! So now we try the next greatest prime number, 173...

Nope! So now we try the next greatest prime number, 179...

Nope! So now we try the next greatest prime number, 181...

Nope! So now we try the next greatest prime number, 191...

Nope! So now we try the next greatest prime number, 193...

Nope! So now we try the next greatest prime number, 197...

Nope! So now we try the next greatest prime number, 199...

Nope! So now we try the next greatest prime number, 211...

Nope! So now we try the next greatest prime number, 223...

Nope! So now we try the next greatest prime number, 227...

Nope! So now we try the next greatest prime number, 229...

Nope! So now we try the next greatest prime number, 233...

Nope! So now we try the next greatest prime number, 239...

Nope! So now we try the next greatest prime number, 241...

Nope! So now we try the next greatest prime number, 251...

Nope! So now we try the next greatest prime number, 257...

Nope! So now we try the next greatest prime number, 263...

Nope! So now we try the next greatest prime number, 269...

Nope! So now we try the next greatest prime number, 271...

Nope! So now we try the next greatest prime number, 277...

Nope! So now we try the next greatest prime number, 281...

Nope! So now we try the next greatest prime number, 283...

Nope! So now we try the next greatest prime number, 293...

Nope! So now we try the next greatest prime number, 307...

Nope! So now we try the next greatest prime number, 311...

Nope! So now we try the next greatest prime number, 313...

Nope! So now we try the next greatest prime number, 317...

Nope! So now we try the next greatest prime number, 331...

Nope! So now we try the next greatest prime number, 337...

Nope! So now we try the next greatest prime number, 347...

Nope! So now we try the next greatest prime number, 349...

Nope! So now we try the next greatest prime number, 353...

Nope! So now we try the next greatest prime number, 359...

No good. 359 is larger than 357. So we're done reducing.

There you have it! The final answer is:
70
51
2
7
=
388
357