The figure shows a circle, a rectangle and a triangle with numbers in them. What is the sum of the numbers inside the circle?

Numbers inside the circle: 12 (circle only), 4 (circle and rectangle), 9 (circle and triangle) and 3 (all three). Sum $=12+4+9+3=28$. 25 forgets the 3, 34 adds the 6 that lies outside every figure, and 12 takes only the circle-only part.