You can put this solution on YOUR website! darrel is half as old as he will be when he is three times as old as he was four years ago.
how old is he?
:
let a = his present age
a = .5(3(a-4))
a = .5(3a - 12)
a = 1.5a - 6
6 = 1.5a - a
6 = .5a
a = 12 his present age
:
:
Check solution in original equation
12 = .5(3(12-4))
12 = .5(3*8); confirms our solution
