This situation models direct proportionality, hence, if one variable increases, the other goes increases as well and vice versa. In this case, the variables are inches and miles.
Part A: Since you multiply 60/25 by 25 to get 60 miles, we know that the value in inches will be 2 * 60/25 = 4.8 inches.
Part B: Since you divide 2 by 8 to get 1/4 inches, we know that the value in miles will be 25 / 8 = 3.125 miles.
Revenue and cost as a function of units sold are and respectively.
we are have to know for which value or input units are these functions at maximum which translates to for how many units is the revenue maximum and for how many same units is our cost minimum.