math help

What is 30/50 + 3/9?

What is 30/50 + 3/9?

Let's add

30
50
+
3
9

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 30 by 9, and get 270, then we multiply 50 by 9 and get 450.

30/50 times 9

Do the same for the second term. We multiply 3 by 50, and get 150, then multiply 50 by 9 and get 450.

3/9 times 50

So now our fractions look like this:

270
450
+
150
450

Step 2

Since our denominators match, we can add the numerators.

270 + 150 = 420

Now we have an answer.

420
450

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:

420
450
÷ 2 =
210
225

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 3...

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

210
225
÷ 3 =
70
75

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:

70
75
÷ 5 =
14
15

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. 17 is larger than 14. So we're done reducing.

And we're done! Here's the final answer to 30/50 + 3/9

30
50
+
3
9
=
14
15
© 2014 Randy Tayler