Question
One year ago Liz was 3 times as old as her brother Jack. In two years she'll only be twice as old as Jack. How old are Liz and Jack now?
Answers
PsyDAG
L - 1 = 3(J - 1)
L + 2 = 2(J +2) = 2J + 4
L = 2J + 2
Substitute 2J + 2 for L in the first equation and solve for J. Insert that value into the last equation to solve for L. Check by putting both values into the first equation.
L + 2 = 2(J +2) = 2J + 4
L = 2J + 2
Substitute 2J + 2 for L in the first equation and solve for J. Insert that value into the last equation to solve for L. Check by putting both values into the first equation.