math help

What is 20/17 + 7/8?

What is 20/17 + 7/8?

This is how we add

20
17
+
7
8

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 20 by 8, and get 160, then we multiply 17 by 8 and get 136.

20/17 times 8

Do the same for the second term. We multiply 7 by 17, and get 119, then multiply 17 by 8 and get 136.

7/8 times 17

So now our fractions look like this:

160
136
+
119
136

Step 2

Since our denominators match, we can add the numerators.

160 + 119 = 279

Now we have an answer.

279
136

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. Try the next prime number, 3...

Nope. Try the next prime number, 5...

Nope. Try the next prime number, 7...

Nope. Try the next prime number, 11...

Nope. Try the next prime number, 13...

Nope. Try the next prime number, 17...

Nope. Try the next prime number, 19...

Nope. Try the next prime number, 23...

Nope. Try the next prime number, 29...

Nope. Try the next prime number, 31...

Nope. Try the next prime number, 37...

Nope. Try the next prime number, 41...

Nope. Try the next prime number, 43...

Nope. Try the next prime number, 47...

Nope. Try the next prime number, 53...

Nope. Try the next prime number, 59...

Nope. Try the next prime number, 61...

Nope. Try the next prime number, 67...

Nope. Try the next prime number, 71...

Nope. Try the next prime number, 73...

Nope. Try the next prime number, 79...

Nope. Try the next prime number, 83...

Nope. Try the next prime number, 89...

Nope. Try the next prime number, 97...

Nope. Try the next prime number, 101...

Nope. Try the next prime number, 103...

Nope. Try the next prime number, 107...

Nope. Try the next prime number, 109...

Nope. Try the next prime number, 113...

Nope. Try the next prime number, 127...

Nope. Try the next prime number, 131...

Nope. Try the next prime number, 137...

No good. 137 is larger than 136. So we're done reducing.

Congratulations! Here's your final answer to 20/17 + 7/8

20
17
+
7
8
=
279
136
© 2014 Randy Tayler