Question 200848
Let r=Robert's age right now



So if "in x years from now, Robert will be k years old", this means that we simply add "x" to "r" to get "k" like so: {{{x+r=k}}}. Now solve for "r" to get {{{r=k-x}}}. So Robert's age right now (in terms of "k" and "x") is {{{k-x}}}



Now just subtract off "m" more years from {{{k-x}}} to get {{{k-x-m}}}



So the answer is C) k-x-m



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Note: if this doesn't make any sense, just plug in some values. Let's say that Robert is 12 years old. So {{{r=12}}}. In two years, he will be 14 (which means k=14). So this means that we'll make {{{x=2}}}. Now how old was Robert 5 years ago (note: m=5)



So plug in {{{k=14}}}, {{{x=2}}} and {{{m=5}}} into {{{k-x-m}}} to get:


{{{14-2-5=12-5=7}}}


So he was 7 years old 5 years ago (from his current age of 12)