math help

What is 45/3 + 5/7?

What is 45/3 + 5/7?

Here's how we add

45
3
+
5
7

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 45 by 7, and get 315, then we multiply 3 by 7 and get 21.

45/3 times 7

Do the same for the second term. We multiply 5 by 3, and get 15, then multiply 3 by 7 and get 21.

5/7 times 3

So now our fractions look like this:

315
21
+
15
21

Step 2

Since our denominators match, we can add the numerators.

315 + 15 = 330

Now we have an answer.

330
21

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...

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:

330
21
÷ 3 =
110
7

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...

No good. 11 is larger than 7. So we're done reducing.

There you have it! Here's the final answer to 45/3 + 5/7

45
3
+
5
7
=
110
7
© 2014 Randy Tayler