There is #3/4# of a box of cereal remaining. You eat #2/5# of the remaining cereal. What fraction of the box did you eat?

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Answer 1 · 2017-10-28T03:02:23

#7/20#

We are dealing with the subtraction of two fractions involving different denominators. We can translate the problem above as:

#3/4-2/5#

We can't just subtract these fractions we must find the LCD (Least Common Denominator)

The LCD between #4# and #5# is #20# so given that, we must manipulate each fraction so that the denominator of each fraction is #20#

#(3/4timescolor(red)(5/5))-(2/5timescolor(blue)(4/4))#

As shown above, we can multiply #3/4# by #5/5# so that the denominator becomes #20#. Similarly, we multiply #2/5# by #4/4#

#(3/4timescolor(red)(5/5))-(2/5timescolor(blue)(4/4))#

#=15/20-8/20#

We can now subtract the fractions:

#=7/20#