math help

What is 25/15 + 6/9?

What is 25/15 + 6/9?

This is how to add

25
15
+
6
9

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 25 by 9, and get 225, then we multiply 15 by 9 and get 135.

25/15 times 9

Now for the second term. You multiply 6 by 15, and get 90, then multiply 15 by 9 and get 135.

6/9 times 15

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

225
135
+
90
135

Step 2

Since our denominators match, we can add the numerators.

225 + 90 = 315

That gives us the sum, which is

315
135

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...

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

315
135
÷ 3 =
105
45

Now, try the same number again.

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

105
45
÷ 3 =
35
15

Now, try the same number again.

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

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

35
15
÷ 5 =
7
3

Now, try the same number again.

No good. 5 is larger than 3. So we're done reducing.

Congratulations! Here's your final answer to 25/15 + 6/9

25
15
+
6
9
=
7
3
© 2014 Randy Tayler