Given cost function is
c(x) = (20 ≤ x ≤ 400)
where x is the number of thousands of square feet
total revenue will be $0.2 million dollars per thousand square feet
Revenue is 0.2 millions per thousand square feet. we know x is the number of thousand of square feet
So R(x) = 0.2x
We know Profit = Revenue - Cost
P(x) = R(x) - C(x)
combine like terms
Profit function is