math help

What is 15/60 + 6/9?

What is 15/60 + 6/9?

This is how to add

15
60
+
6
9

Step 1

Of course, you can't add two fractions if the denominators (bottom numbers) don't match. To get a common denominator, multiply the denominators together. Then we fix the numerators by multiplying each one by their other term's denominator.

Now you 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 6 by 60, and get 360, then multiply 60 by 9 and get 540.

6/9 times 60

The problem now has new fractions to add:

135
540
+
360
540

Step 2

Since our denominators match, we can add the numerators.

135 + 360 = 495

This yields the answer

495
540

Step 3

The last step is to reduce the fraction if we can.

To find out, we try dividing 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:

495
540
÷ 3 =
165
180

Let's try dividing by that again...

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

165
180
÷ 3 =
55
60

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:

55
60
÷ 5 =
11
12

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...

No good. 13 is larger than 11. So we're done reducing.

There you have it! Here's the final answer to 15/60 + 6/9

15
60
+
6
9
=
11
12
© 2014 Randy Tayler