math help

What is 100/72 + 4/5?

What is 100/72 + 4/5?

This is how to add

100
72
+
4
5

Step 1

We still have different denominators (bottom numbers), though, so we need to get a common denominator. This will make the bottom numbers match. Multiply the denominators together first. Now, multiply each numerator by the other term's denominator.

Now we multiply 100 by 5, and get 500, then we multiply 72 by 5 and get 360.

100/72 times 5

Now for the second term. You multiply 4 by 72, and get 288, then multiply 72 by 5 and get 360.

4/5 times 72

This gives us a new problem that looks like so:

500
360
+
288
360

Step 2

Since our denominators match, we can add the numerators.

500 + 288 = 788

So what's the answer so far?

788
360

Step 3

Can this fraction be reduced?

First, we attempt to divide it by 2...

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

788
360
÷ 2 =
394
180

Now, try the same number again.

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

394
180
÷ 2 =
197
90

Now, try the same number again.

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

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

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

Nope. Try the next prime number, 11...

Nope. Try the next prime number, 13...

Nope. Try the next prime number, 17...

Nope. Try the next prime number, 19...

Nope. Try the next prime number, 23...

Nope. Try the next prime number, 29...

Nope. Try the next prime number, 31...

Nope. Try the next prime number, 37...

Nope. Try the next prime number, 41...

Nope. Try the next prime number, 43...

Nope. Try the next prime number, 47...

Nope. Try the next prime number, 53...

Nope. Try the next prime number, 59...

Nope. Try the next prime number, 61...

Nope. Try the next prime number, 67...

Nope. Try the next prime number, 71...

Nope. Try the next prime number, 73...

Nope. Try the next prime number, 79...

Nope. Try the next prime number, 83...

Nope. Try the next prime number, 89...

Nope. Try the next prime number, 97...

No good. 97 is larger than 90. So we're done reducing.

Congratulations! Here's your final answer to 100/72 + 4/5

100
72
+
4
5
=
197
90
© 2014 Randy Tayler