math help

What is 15/60 + 4/9?

What is 15/60 + 4/9?

Here's how we add

15
60
+
4
9

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 9, and get 135, then we multiply 60 by 9 and get 540.

15/60 times 9

Do the same for the second term. We multiply 4 by 60, and get 240, then multiply 60 by 9 and get 540.

4/9 times 60

So now our fractions look like this:

135
540
+
240
540

Step 2

Since our denominators match, we can add the numerators.

135 + 240 = 375

So the answer is:

375
540

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...

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

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

375
540
÷ 3 =
125
180

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:

125
180
÷ 5 =
25
36

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...

Nope. Try the next prime number, 23...

Nope. Try the next prime number, 29...

No good. 29 is larger than 25. So we're done reducing.

Congratulations! Here's your final answer to 15/60 + 4/9

15
60
+
4
9
=
25
36
© 2014 Randy Tayler