Objects in image: Ruler
Text visible in image: 18, 19, 20, 21, 22, 4, 45, 46, 47, 48, 49, 5/0, 51, 5/2, 5/3, 5/4, 5/5, 5/6, 5/7
Question: what is the number in the middle of the top half of the ruler?
Answers: 20, 20, 20, 20, 20, 20, 20,  20, 20, 21