It would be a. because a rectangle has 2 pairs of congruent sides so since the width is 12 and there are 2 sides with that measurement it would be 2(12) and the same goes for the length, and then you add them together.
So what you do is take 3.50 then subtract 1.50 to get the profit of one cup of coffee. ($2) Then you do the $100 and divide it by the $2 and find out how many cups of coffee he has to sell to get to the $100. (50)