math help

What is 72/63 + 1/5?

What is 72/63 + 1/5?

Let's add

72
63
+
1
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 72 by 5, and get 360, then we multiply 63 by 5 and get 315.

72/63 times 5

Now for the second term. You multiply 1 by 63, and get 63, then multiply 63 by 5 and get 315.

1/5 times 63

This gives us a new problem that looks like so:

360
315
+
63
315

Step 2

Since our denominators match, we can add the numerators.

360 + 63 = 423

So what's the answer so far?

423
315

Step 3

Can this fraction be reduced?

First, we attempt to divide 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:

423
315
÷ 3 =
141
105

Let's try dividing by that again...

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

141
105
÷ 3 =
47
35

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...

Nope! So now we try the next greatest prime number, 31...

Nope! So now we try the next greatest prime number, 37...

No good. 37 is larger than 35. So we're done reducing.

There you have it! Here's the final answer to 72/63 + 1/5

72
63
+
1
5
=
47
35
© 2014 Randy Tayler