math help

What is 1/15 + 5/9?

What is 1/15 + 5/9?

This is how you add

1
15
+
5
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 1 by 9, and get 9, then we multiply 15 by 9 and get 135.

1/15 times 9

Do the same for the second term. We multiply 5 by 15, and get 75, then multiply 15 by 9 and get 135.

5/9 times 15

The problem now has new fractions to add:

9
135
+
75
135

Step 2

Since our denominators match, we can add the numerators.

9 + 75 = 84

The sum we get is

84
135

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:

84
135
÷ 3 =
28
45

Let's try dividing by that again...

Nope! So now we try the next greatest prime number, 5...

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 28. So we're done reducing.

There you have it! Here's the final answer to 1/15 + 5/9

1
15
+
5
9
=
28
45
© 2014 Randy Tayler