Brain Teaser

Answer: The daughter received $40, and the son received $50.

Let D be the amount of money that Dr. Johnson’s daughter received, and S be the amount of money that Dr. Johnson’s son received. Then we have:
D+S=90 or S = 90 – D
2 x (D-10) = S + 10 or 2D = S + 30 which implies 2D = 90 – D + 30. Solving for D, we get D= 40, and, therefore, S = 50.