In the figure an ellipse, a circle and a rectangle overlap. What is the sum of the numbers that lie inside the rectangle but outside the ellipse?

Inside the rectangle and not in the ellipse: 13 (rectangle only) and 6 (rectangle and circle only), so the sum is $13+6=19$. 32 takes every number in the rectangle, 13 only the rectangle-only part, and 21 wrongly adds the 2 that is also inside the ellipse.