P(x) = -x 3 + x 2 - 60x + 100, x ≥ 5 is an approximation to the total profit (in thousands of dollars) from the sale of x hundred thousand tires. find the number of tires that must be sold to maximize profit.

it will cost dollar $540

the living room is 3 which means if we divide 325/3 then we get $108

therefore if 1part of the living room cost $108 and 3 costed $325

then total 5part of the room will cost 5*108 which gives $540