A man is 42 years old and his son is 12 years old. In how many years will the age of the son be half the age of the man at that time? Explain!

Question

A man is 42 years old and his son is 12 years old. In how many years will the age of the son be half the age of the man at that time? Explain! I've not tried anything. 

Answer 1

Let x = the unknown number of years

 

The man is now 42 and his son is 12.  In x years, this is how old they'll be:

 

Man's Age = (42 + x) years old

Son's Age  = (12 + x) years old

 

Now in x years, the son will be one-half as old as his dad.  That's the key piece of information that allows us to equate their two ages:

 

Son's Age = (1/2)*Man's Age

12 + x      =   (1/2)*(42 + x)

12 + x = 21 + x/2

 

Now solve for x and let me know what you get (in the comments) and I'll tell you if you got it right.