Question 165032
I want to do more than answer it, I want to show you how to do it.
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A man is now 42 years old and his friend is 33 years old. How many years ago was the man twice as old as his friend was then?
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Let t = number of yrs for this to be true
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Subtract t from both sides and make an equation:
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Man, t yrs ago, was twice as old, as his friend t yrs ago
42 - t = 2(33 - t)
42 - t = 66 - 2t; multiply what's inside the brackets
Some basic algebra operations
+2t - t = 66 - 42
t = 24 yrs ago
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We can prove this 
42 - 24 = 18;
33 - 24 = 9 
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2. Paul is 3 years younger than his friend Peter. In seven years the product of their ages will be five more than the product of their ages 5 years ago. How old are they now? 
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This problem is impossible, there is no way that the product 7 yrs from now
will be only 5 more than the product 5 yrs ago