Consumers willingness to spend

Suppose that the consumers demand function for a certain commodity is **D(q)=50-3q-q^2** dollars per unit:

A. Find the number of Units that will be bought if the market price is $32 per unit.

**I got q=3 which was right but I got part B wrong!**

B.Compute the consumers willingness to spend to get the number of Units in part (a).

**I got 31.50 but that was the answer to part c! I just want to see how its done for part B so I have the right answer so I can use the material to study for my final exam...Thanks!**