A shipping company charges to ship packages based on the mass of the package. For packages weighing up to and including 3 kg, the cost is $7.65. For packages weighing greater than 3 kg to 8 kg, the cost is $14.95 to ship. For packages greater than 8 kg to 18 kg, the cost is $32.55. For packages greater than 18 kg to 30 kg, the cost is $70.85 to ship. And for packages greater than 30 kg to 45 kg, it costs $149.95 to ship.

a) Graph the situation on a coordinate grid.

b) State the domain and range of the relation.

c) Explain why this relation must be a function