
Mike S. answered 01/17/20
SAT/ACT & Math Tutor- Recent Notre Dame Grad
First, we want to translate this problem into algebraic equations
Define the variables
J = Joe's Age
T = Tom's Age
From the first sentence, we see that Joe's age is twice Tom's age. We write that as the following:
J = 2T
From the second sentence, we see that 6 years ago, Joe's age was 3 times Tom's age. Before multiplying Tom's age by 3, we would subtract 6 from both T and J. Then, we write that as the following and simplify:
J - 6 = 3*(T - 6) Distribute 3 to the T and -6
J - 6 = 3T - 18 Combine like terms
J + 12 = 3T
Now that we have a system of equations, we can substitute our value for J in the first equation, into the second equation:
(2T) + 12 = 3T
Subtract 2T from both sides:
12 = T
Plug this value into one of the prior equations:
J = 2*12
J = 24