How do you simplify 1/4 + 1/5?

2 Answers
May 6, 2018

:. 9/20

Explanation:

To simplify 1/4 + 1/5, we need to make both of the fractions as the same base.

=> (1)/4 + 1/5

=> 5/20 + 4/20

:. 9/20

May 6, 2018

Rewrite each fraction so they have the same denominator.

Explanation:

Least Common Multiple (LCM) Route:

Multiples of 4 are 4, 8, 12, 16, 20, 24, 28
Multiples of 5 are 5, 10 ,15, 20, 25, 30
The Smallest Multiple that 4 and 5 have in common is 20.

Change 1/4 to a denominator of 20 by multiplying top and bottom by 5: 1/4 * 5/5 = 5/20.

Change 1/5 to a denominator of 20 by multiplying top and bottom by 4: 1/5 * 4/4 = 4/20.

Now Add the 2 new fractions together and simplify if possible:
5/20 + 4/20 = 9/20

Cross Multiply Route:
a/c + b/d = (ad + bc)/(cd)

1/4 + 1/5 = (1*5 + 1*4)/(4*5) = (5 + 4)/20 = 9/20

Remember to always Simplify if possible.