Mary is 24 years old. Let Ann be A years old. Mary is twice as old as Ann was x years ago, which was (A - x). Also x years ago, Mary was (24 - x), and that is how old Ann is now, which is A. x years ago, Mary was 24 - x x years ago, Ann was A - x So the equations comes from:= 2· and = So the system of equations is 24 = 2(A - x) 24 - x = A Solve that system and get x = 6 and A = 18. So 6 years ago Ann was 12 and Mary is twice that now. Edwin