A teacher has two students, one three times as old as the other. The teacher is five times as old as the older student, and in 5 years she will be five times as old as her younger student. Find the teacher’s present age.

Answer 1

S = 3s ... t = 5S = 15s

t + 5 = 5(s + 5) = 5s + 25

3t + 15 = 15s + 75

substituting ... 3t + 15 = t + 75

solve for t

Answer 2

That is wrong - the answer is 40