d'Artagnan, Athos, Porthos, and Aramis are good friends and passionate readers of modern fiction. When Alexandre Dumas's new book "The Three Musketeers came out last month, they all went to buy a copy. The price was 5 francs. Their willingness to pay were as follows d'Artagnant 3 francs, Athos: 30 francs, Porthos: francs, and Aramis: 20 francs. Assuming there was no shortage of the book, the total consumer surplus was
a 110 francs
b 70 francs
c 90 francs
d 50 francs
e We cannot compute the total consumer surplus without information about the costs