Help on question 12

Some years ago it was estimated that the demand for steel approximately satisfied the equation p = 148 - 10x, and the total cost of producing x units of steel was C(x) = 100 + 48x. (The quantity x was measured in millions of tons and the price and total cost were measured in millions of dollars.) Determine the level of production and the corresponding price that maximize the profits. . . . The maximum profit occurs at x = (million tons) The corresponding price is dollars per ton