The correct answer is $45
Mark and Rasheed are at the bookstore buying new calculators for the semester. Mark is willing to pay $75 ( $75 - $65 = $10 ) and Rasheed is willing to pay $100 ( $100 - $65 = $35 ) for a graphing calculator. The price for a calculator at the bookstore is $65. Their total consumer surplus ( $10 + $35 = $45 ) is $45