math help

What is 25/15 + 4/8?

What is 25/15 + 4/8?

This is how we add

25
15
+
4
8

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 25 by 8, and get 200, then we multiply 15 by 8 and get 120.

25/15 times 8

Do the same for the second term. We multiply 4 by 15, and get 60, then multiply 15 by 8 and get 120.

4/8 times 15

So now our fractions look like this:

200
120
+
60
120

Step 2

Since our denominators match, we can add the numerators.

200 + 60 = 260

Now we have an answer.

260
120

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...

Are both the numerator and the denominator evenly divisible by 2? Yes! So we reduce it:

260
120
÷ 2 =
130
60

Now, try the same number again.

Are both the numerator and the denominator evenly divisible by 2? Yes! So we reduce it:

130
60
÷ 2 =
65
30

Now, try the same number again.

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

Nope. Try the next prime number, 5...

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

65
30
÷ 5 =
13
6

Now, try the same number again.

Nope. Try the next prime number, 7...

No good. 7 is larger than 6. So we're done reducing.

Congratulations! Here's your final answer to 25/15 + 4/8

25
15
+
4
8
=
13
6
© 2014 Randy Tayler