Luke is building a storage building and needs to have a slab of concrete poured. he knows the contractor charges an initial cost of $95 plus an additional $3.50 per square foot of concrete. which function can be used to determine the cost, in dollars, to pour a concrete slab with an area of x square feet? a) f(x) = 3.5x + 95 b) f(x) = 9.5x + 3.5 c) f(x) = 95x + 3.5 d) f(x) = 98.5x