The figure shows a circle, a rectangle and a triangle. What is the sum of the numbers that lie inside the rectangle or the triangle but NOT inside the circle?

Outside the circle but inside the rectangle or the triangle: 15 (rectangle only), 4 (triangle only) and 12 (rectangle and triangle). Sum $=15+4+12=31$. 36 adds the 5 that is outside every figure, 52 also takes the numbers inside the circle, and 19 leaves out the 12.