Phil ate #2/5# of a pizza, Caroline ate #1/4# of a pizza. How much did they eat in all?

2 Answers
Mar 24, 2018

#13/20# of a pizza

Explanation:

Convert each fraction so that it has a common denominator. 5 and 4 are common factors of 20, so let's use 20 in the denominator.

#2/5=2/5*1=2/5*4/4=8/20#

#1/4=1/4*1=1/4*5/5=5/20#

Now it's easy to add them:

#8/20+5/20=13/20#

Mar 24, 2018

Phil and Caroline ate #13/20# of the pizza in all.

Explanation:

The lowest common multiple of #5# and #4# is 20.

#20/5 = 4#
Multiplying the numerator and denominator of #2/5# by #4#:
#(2*4)/(5*4) = 8/20#

#20/4 = 5#
Multiplying the numerator and denominator of #1/4# by #5#:
#(1*5)/(4*5) = 5/20#

Now that both fractions have the same denominator, we can add their numerators and keep the same denominator.
#2/5 + 1/4 = 8/20 + 5/20 = 13/20#