Demand,Revenue, & the Largest Reduction to maximize Revenue
200 DVD players are sold per week for $300 each. For each $10 rebate (reduction in sale price), 20 additional DVD players are sold.

Find the demand, the revenue, and the largest reduction (multiple of 10) to maximize revenue.

Cost: c(x)
Marginal Cost: c'(x)
Revenue: R(x)= x(p(x))
Demand: p(x)
Marginal Revenue: R'(x)
Profit: P(x)=R(x) - c(x)