math help

What is 7/9 + 5/10?

What is 7/9 + 5/10?

This is how we add

7
9
+
5
10

Step 1

Can you add yet? Nope! The denominators don't match. We need a common denominator. So next we take both denominators and multiply them. Next, take each numerator and multiply it by the denominator of the other term.

So, we multiply 7 by 10, and get 70, then we multiply 9 by 10 and get 90.

7/9 times 10

Now for the second term. You multiply 5 by 9, and get 45, then multiply 9 by 10 and get 90.

5/10 times 9

We now have a new problem, that looks like this:

70
90
+
45
90

Step 2

Since our denominators match, we can add the numerators.

70 + 45 = 115

That gives us the sum, which is

115
90

Step 3

Now, do we need to simplify this fraction?

First, we attempt to divide it by 2...

Nope. Try the next prime number, 3...

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

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

115
90
÷ 5 =
23
18

Now, try the same number again.

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...

No good. 19 is larger than 18. So we're done reducing.

Congratulations! Here's your final answer to 7/9 + 5/10

7
9
+
5
10
=
23
18
© 2014 Randy Tayler