math help

What is 15/60 + 5/8?

What is 15/60 + 5/8?

Here's how we add

15
60
+
5
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 15 by 8, and get 120, then we multiply 60 by 8 and get 480.

15/60 times 8

Do the same for the second term. We multiply 5 by 60, and get 300, then multiply 60 by 8 and get 480.

5/8 times 60

So now our fractions look like this:

120
480
+
300
480

Step 2

Since our denominators match, we can add the numerators.

120 + 300 = 420

So the answer is:

420
480

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...

Are both the numerator and the denominator evenly divisible by 2? Yes! So we reduce it:

420
480
÷ 2 =
210
240

Now, try the same number again.

Are both the numerator and the denominator evenly divisible by 2? Yes! So we reduce it:

210
240
÷ 2 =
105
120

Now, try the same number again.

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

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

105
120
÷ 3 =
35
40

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
40
÷ 5 =
7
8

Now, try the same number again.

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

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

No good. 11 is larger than 7. So we're done reducing.

Congratulations! Here's your final answer to 15/60 + 5/8

15
60
+
5
8
=
7
8
© 2014 Randy Tayler