SOLUTION: Ten years ago, Alfred's age was three times that of his son Jerry. Fifteen years from now, Alfred's age will be twelve less than twice of Jerry's age. How old are they now?

Algebra ->  Customizable Word Problem Solvers  -> Age -> SOLUTION: Ten years ago, Alfred's age was three times that of his son Jerry. Fifteen years from now, Alfred's age will be twelve less than twice of Jerry's age. How old are they now?      Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


   



Question 919049: Ten years ago, Alfred's age was three times that of his son Jerry. Fifteen years from now, Alfred's age will be twelve less than twice of Jerry's age. How old are they now?
Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!

10 years ago Alfred's age was 3 times that of his son Jerry.
Alfred-10=3%28Jerry-10%29.........eq.1
15 years from now Alfred's age will be 12 less than twice of Jerry age
Alfred%2B15=2%28Jerry%2B15%29-12.........eq.2
solve the system:
Alfred-10=3%28Jerry-10%29.........eq.1
Alfred%2B15=2%28Jerry%2B15%29-12.........eq.2
___________________________
Alfred-10=3%28Jerry-10%29.........eq.1 solve for Alfred
Alfred=3%28Jerry-10%29%2B10
Alfred=3Jerry-30%2B10
Alfred=3Jerry-20.......substitute in eq.2

Alfred%2B15=2%28Jerry%2B15%29-12.........eq.2..solve for Jerry
3Jerry-5=2Jerry%2B30-12
3Jerry-2Jerry=5%2B18
highlight%28Jerry=23%29


find Alfred=3Jerry-20
Alfred=3%2A23-20
Alfred=69-20
highlight%28Alfred=49%29

check:
10 years ago Alfred's age was 49-10=39 and Jerry's age was 23-10=13
as you can see, 39 is times times more than 13

15 years from now Alfred's age will be 49%2B15=64 and Jerry's age will be 23%2B15=38
than twice of Jerry age is 2%2A38=76 and 76-64=12