math help

What is 25/15 + 2/9?

What is 25/15 + 2/9?

This is how you add

25
15
+
2
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 2 by 15, and get 30, then multiply 15 by 9 and get 135.

2/9 times 15

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

225
135
+
30
135

Step 2

Since our denominators match, we can add the numerators.

225 + 30 = 255

Answer:

255
135

Step 3

Now, do we need to simplify this fraction?

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

Nope! So now we try the next greatest prime number, 3...

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

255
135
÷ 3 =
85
45

Let's try dividing by that again...

Nope! So now we try the next greatest prime number, 5...

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

85
45
÷ 5 =
17
9

Let's try dividing by that again...

Nope! So now we try the next greatest prime number, 7...

Nope! So now we try the next greatest prime number, 11...

No good. 11 is larger than 9. So we're done reducing.

There you have it! Here's the final answer to 25/15 + 2/9

25
15
+
2
9
=
17
9
© 2014 Randy Tayler