math help

What is 7/20 + 3/6?

What is 7/20 + 3/6?

Let's add

7
20
 +
3
6

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 7 by 6, and get 42, then we multiply 20 by 6 and get 120.

7/20 times 6

Do the same for the second term. We multiply 3 by 20, and get 60, then multiply 20 by 6 and get 120.

3/6 times 20

So now our fractions look like this:

42
120
 +
60
120

Step 2

Since our denominators match, we can add the numerators.

42 + 60 = 102

Now we have an answer.

102
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:

102
120
 ÷ 2 =
51
60

Let's try dividing by that again...

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:

51
60
 ÷ 3 =
17
20

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...

No good. 19 is larger than 17. So we're done reducing.

There you have it! Here's the final answer to 7/20 + 3/6

7
20
 +
3
6
 =
17
20
© 2014 Randy Tayler

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