math help

What is 25/15 + 1/9?

What is 25/15 + 1/9?

Let's add

25
15
+
1
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 25 by 9, and get 225, then we multiply 15 by 9 and get 135.

25/15 times 9

Do the same for the second term. We multiply 1 by 15, and get 15, then multiply 15 by 9 and get 135.

1/9 times 15

The problem now has new fractions to add:

225
135
+
15
135

Step 2

Since our denominators match, we can add the numerators.

225 + 15 = 240

This yields the answer

240
135

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:

240
135
÷ 3 =
80
45

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:

80
45
÷ 5 =
16
9

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. 11 is larger than 9. So we're done reducing.

And we're done! Here's the final answer to 25/15 + 1/9

25
15
+
1
9
=
16
9
© 2014 Randy Tayler