Company makes tire rims. Estimates the the profit, P, of selling x tire rims is given by: P= -0.01x^2 + 8x + 1500

Plugging in 1000 for P and solving, I get 400. Is that correct?

b) find the number of rims that must be sold to maximize profit.

plugging in 400 for x, I get $3100.

Did I set up and solve these two correctly? thank you for your time.

Looks good to me