The price–demand equation and the cost function for the production of garden hoses are given, respectively, by 

p = 20 - √x and C(x) = 500 + 2x

where x is the number of garden hoses that can be sold at a price of $p per unit and C(x) is the total cost (in dollars) of producing x garden hoses.

(A) Express the revenue function in terms of x.

(B) Graph the cost function and revenue function in the same viewing window for 0 ≤ x ≤ 400. Use approximation techniques to find the break-even points correct to the nearest unit.