demand equation

Assume that a demand equation is given by  q=7000−100p.

Find the marginal revenue for the given production levels (values of q). (Hint: Solve the demand equation for p and use R(q)=qp.)

a. The marginal revenue at 2000 units is _____. (Simplify youranswer.)

b. The marginal revenue at 3500 units is _____. (Simplify youranswer.)

c. The marginal revenue at 6500 units is ______. (Simplify youranswer.)