Which equation can be used to determine p, the cost of b mats? p = 10.50 + b b = 10.50 + p b = 10.50p p = 10.50b

Since you want to find p, you're looking for an equation that has

p = <something>

Generally, cost functions multiply the unit cost by the number of units. Here, you're told the number of units is represented by b, so you will be looking for an equation of the form

p = (unit cost)(b)

The last selection has this form

p = 10.50b

As you look thru the 4 answer choices, elim. any that do not begin with "p=."

Please note: I suspect that one of your answer choices was p(b) = $10.50p. If that's the case, please make sure to include the "(b)" part, as p(b) denotes "p is a function of b."

The independent variable here is b, the number of mats; the dependent var. is p, the cost of b mats. Thus, p = f(b).