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What is 78/73 - 2/5?

What is 78/73 - 2/5?

Here's how to subtract 2/5 from 78/73:

78
73
2
5

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 78 by 5, and get 390.

Then we multiply 2 by 73, and get 146.

Next we give both terms new denominators -- 73 × 5 = 365.

So now our fractions look like this:

390
365
146
365

Step 2

Since our denominators match, we can subtract the numerators.

390 − 146 = 244

So the answer is:

244
365

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...

No good. 251 is larger than 244. So we're done reducing.

There you have it! The final answer is:
78
73
2
5
=
244
365