Easy way to solve?

[aubrey.hemingway@aruplab.com]

Will someone please help me remember how to solve this problem. We went over it in class but I can't make sense of it now. The question comes from Quiz 1, Plugging Numbers & Plugging Answers.

9. Each cartoonist for the local newspaper is paid as follows: c dollars
for each of the first n cartoons each month, and c + d for each
cartoon thereafter, where c > d. How many more dollars will a
cartoonist who submits n + c cartoons in a month earn than a
cartoonist who submits n + d cartoons?
a) (c - d)(c + d + n)
b) c – d
c) c2 - d2
d) n(c – d)
e) cn + dn – cn

Thank you!