math help

What is 88/15 + 7/12?

What is 88/15 + 7/12?

This is how we add

88
15
+
7
12

Step 1

Of course, you can't add two fractions if the denominators (bottom numbers) don't match. To get a common denominator, multiply the denominators together. Then we fix the numerators by multiplying each one by their other term's denominator.

Now you multiply 88 by 12, and get 1056, then we multiply 15 by 12 and get 180.

88/15 times 12

Do the same for the second term. We multiply 7 by 15, and get 105, then multiply 15 by 12 and get 180.

7/12 times 15

The problem now has new fractions to add:

1056
180
+
105
180

Step 2

Since our denominators match, we can add the numerators.

1056 + 105 = 1161

This yields the answer

1161
180

Step 3

The last step is to reduce the fraction if we can.

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

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

Are both the numerator and the denominator evenly divisible by 3? Yes! So we reduce it:

1161
180
÷ 3 =
387
60

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

Are both the numerator and the denominator evenly divisible by 3? Yes! So we reduce it:

387
60
÷ 3 =
129
20

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 5...

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. 23 is larger than 20. So we're done reducing.

And we're done! Here's the final answer to 88/15 + 7/12

88
15
+
7
12
=
129
20
© 2014 Randy Tayler