math help

What is 30/50 + 5/7?

What is 30/50 + 5/7?

Let's add

30
50
+
5
7

Step 1

We can't add two fractions with different denominators (the bottom number). So you need to get a common denominator - both bottom numbers need to match. 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 30 by 7, and get 210, then we multiply 50 by 7 and get 350.

30/50 times 7

Do the same for the second term. We multiply 5 by 50, and get 250, then multiply 50 by 7 and get 350.

5/7 times 50

So now our fractions look like this:

210
350
+
250
350

Step 2

Since our denominators match, we can add the numerators.

210 + 250 = 460

Now we have an answer.

460
350

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...

Are both the numerator and the denominator evenly divisible by 2? Yes! So we reduce it:

460
350
÷ 2 =
230
175

So far so good... let's try to divide by that number again.

No good. So next you try the next prime number, which is 3...

No good. So next you try the next prime number, which is 5...

Are both the numerator and the denominator evenly divisible by 5? Yes! So we reduce it:

230
175
÷ 5 =
46
35

So far so good... let's try to divide by that number again.

No good. So next you try the next prime number, which is 7...

No good. So next you try the next prime number, which is 11...

No good. So next you try the next prime number, which is 13...

No good. So next you try the next prime number, which is 17...

No good. So next you try the next prime number, which is 19...

No good. So next you try the next prime number, which is 23...

No good. So next you try the next prime number, which is 29...

No good. So next you try the next prime number, which is 31...

No good. So next you try the next prime number, which is 37...

No good. 37 is larger than 35. So we're done reducing.

And we're done! Here's the final answer to 30/50 + 5/7

30
50
+
5
7
=
46
35
© 2014 Randy Tayler