1. The wording tells you the independent variable: it is the phrase following "based on" or "depends on." The other variable is the dependent variable. Your variables are (independent, dependent) ...
A) (expenses, cost of running the business)
B) (area, house price)
C) (distance, time to run it)
D) (size of the carton, number of items in it)
2. f(h) = 7h . . . . . . . where h is the number of hours of babysitting and f(h) is the cost of babysitting. 0 ≤ h ≤ 4 is the domain for which this function is defined.