Weight(lb): 4,5,46

Question

Total Cost($): 17.40,21.75,200.10

a.proportional? _________
b.equation? _______
c.weight: __________
d. total cost: ________

My answers:
a. Yes
b. Y=4.35x
c. don't have one
d. don't have one

I am no sure how to find the answers for c and d, please help