Joe's income is $500, the price of food (F) is $2 per unit, and the price of shelter (S) is $100. Which of the following represents his budget constraint?
A) 500 = 100F + 2S
B) 500 = 2F + 100S
C) S = 500 - 2F
D) All of the above.
Answer: 500 = 2F + 100S