A teacher has two students, one two 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.

Let x = the older student

Let y = the younger student

Let z = the teacher.

x = 2y

z = 5x

z + 5 = 5y Somehow this does not look like its going to be nice.

z = 5y - 5

Since z = 5y - 5 we have

5y - 5 = 5x

y - 1 = x Here's the problem. there is a contradiction. You need to make y bigger, not smaller.