Suppose tuna is on sale for $0.90 a can, and you have a coupon for $0.40 off your total purchase. write a function rule for the cost of n cans of tuna.

AC(n) = 0.09n- 0.40
BC(n) = 0.40n - 0.90
CC(n) = (0.90 + n) - 0.40
DC(n) = (0.40 + n) - 0.90