Tickets to a museum cost $12 for each adult and $9 for each child. what would be the best choice for variable(s) when writing an expression for the total cost of attending the museum?
a. t would represent the total number of tickets sold
b. a would represent the total area/square footage of the museum
c. a would represent the total number of adult tickets bought, and c would represent the total number of child tickets bought
d. a would represent the cost per adult ticket, and c would represent the cost per child ticket