SOLUTION: in x years from now, Robert will be k years old. How old was Robert m years ago? The possible answers are: a) x-(k+m) b) k-x

Question 200848: in x years from now, Robert will be k years old. How old was Robert m years ago?
The possible answers are: a) x-(k+m)
b) k-x
c) k-x-m
d) x-(k-m)
e) k+m-x

Thank you for helping me!
Answer by jim_thompson5910(35256) (Show Source): You can put this solution on YOUR website!
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: . Now solve for "r" to get . So Robert's age right now (in terms of "k" and "x") is

Now just subtract off "m" more years from to get

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 . In two years, he will be 14 (which means k=14). So this means that we'll make . Now how old was Robert 5 years ago (note: m=5)

So plug in , and into to get:

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