A city has $600,000 to purchase new vehicles for the parks department. They are considering purchasing a mix of SUVs costing $28,000 each and trucks costing $40,000 each.

a) They can buy 12 SUVs and 10 trucks.
b) They can buy 20 SUVs and 10 trucks.
c) They can buy 15 SUVs and 12 trucks.
d) They can buy 10 SUVs and 15 trucks.