math help

What is 1/15 + 7/10?

What is 1/15 + 7/10?

Here's how you add

1
15
+
7
10

Step 1

We still have different denominators (bottom numbers), though, so we need to get a common denominator. This will make the bottom numbers match. Multiply the denominators together first. Now, multiply each numerator by the other term's denominator.

Now we multiply 1 by 10, and get 10, then we multiply 15 by 10 and get 150.

1/15 times 10

Now for the second term. You multiply 7 by 15, and get 105, then multiply 15 by 10 and get 150.

7/10 times 15

This gives us a new problem that looks like so:

10
150
+
105
150

Step 2

Since our denominators match, we can add the numerators.

10 + 105 = 115

That gives us an answer of

115
150

Step 3

Can this fraction be reduced?

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

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

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:

115
150
÷ 5 =
23
30

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...

Nope! So now we try the next greatest prime number, 13...

Nope! So now we try the next greatest prime number, 17...

Nope! So now we try the next greatest prime number, 19...

Nope! So now we try the next greatest prime number, 23...

Nope! So now we try the next greatest prime number, 29...

No good. 29 is larger than 23. So we're done reducing.

There you have it! Here's the final answer to 1/15 + 7/10

1
15
+
7
10
=
23
30
© 2014 Randy Tayler