A small grocery store offers two different brands of milk.

Brand A 2% milk costs $3.50 a gallon.
Brand B whole organic milk costs $3.00 for a half-gallon plus a one-time deposit of $1.50 for the glass jug. Once the glass jug deposit has been paid, the jug can be brought back to the store and the deposit doesn't have to be paid for each additional half-gallon milk that is purchased.
Graph the cost of milk for the brand that is proportional.

PLEASE HELP ME ANSWER, BEEN AT IT ALL DAY PLEASE! THANKS! :3