Steply

Simplify (1/3 + 1/6)/(1/2 - 1/4)

Step by step, with the reason for every step · Complex fractions · Algebra 2

Step by step

The question

Question: simplify this fraction.

On top: 1/3 + 1/6.

At the bottom: 1/2 − 1/4.

A fraction with fractions inside is called a complex fraction.

13 + 1612 − 14

1 Find the common bottom

The small fractions have bottoms 3, 6, 2 and 4.

The smallest thing they all go into is 12.

12 is in the 3 and 6 and 2 and 4 times tables.

small bottoms: 3, 6, 2, 4
common bottom: 12

2 Times 12 on top and bottom

12/12 is 1.

Times 1 does not change the value.

1212 = 1

We multiply the top and the bottom by 12.

Then the small fractions go away.

= 12 × (13 + 16)12 × (12 − 14)

3 Multiply every part

Every part times 12.

12 times 1/3: the bottom 3 goes into 12, so we get 4.

12 times 1/6: the bottom 6 goes into 12, so we get 2.

12 × 13 = 4
12 × 16 = 2
12 × 12 = 6
12 × (−14) = −3

So we get (4 + 2)/(6 − 3).

No more small fractions!

= 4 + 26 − 3

Like terms go together: 6/3.

= 63

4 Simplify

Every part, on the top and the bottom, can be divided by 3.

So we divide the top and the bottom by it.

÷ 3: 6 → 2
÷ 3: 3 → 1

So the answer is 2.

= 2

5 Check

Let's check the long way: work out the top and the bottom first.

The top is 1/2, the bottom is 1/4.

top: 26 + 16 = 12, bottom: 24 − 14 = 14

Then top divided by bottom: times the flip.

We get 2 again.

It works!

12 ÷ 14 = 12 × 4 = 2

Let's look back.

First: find the common bottom.

Then: times 12 on top and bottom.

Then: multiply every part.

Then: simplify.

Last: check.

Answer
= 2

Your turn

Try this one yourself, then check:

simplify (14 + 16) ÷ (13 − 18)
Show the answer
2

More from Complex fractions

The whole lesson: Complex fractions →