math help

What is 15/60 + 2/9?

What is 15/60 + 2/9?

This is how you add

15
60
+
2
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 2 by 60, and get 120, then multiply 60 by 9 and get 540.

2/9 times 60

The problem now has new fractions to add:

135
540
+
120
540

Step 2

Since our denominators match, we can add the numerators.

135 + 120 = 255

The sum we get is

255
540

Step 3

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

To find out, we try dividing it by 2...

No good. So next you try the next prime number, which is 3...

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

255
540
÷ 3 =
85
180

So far so good... let's try to divide by that number again.

No good. So next you try the next prime number, which is 5...

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

85
180
÷ 5 =
17
36

So far so good... let's try to divide by that number again.

No good. So next you try the next prime number, which is 7...

No good. So next you try the next prime number, which is 11...

No good. So next you try the next prime number, which is 13...

No good. So next you try the next prime number, which is 17...

No good. So next you try the next prime number, which is 19...

No good. 19 is larger than 17. So we're done reducing.

And we're done! Here's the final answer to 15/60 + 2/9

15
60
+
2
9
=
17
36
© 2014 Randy Tayler