2007 AMC 10A Problem 1

One ticket to a show costs \$20 at full price. Susan buys 4 tickets using a coupon that gives her a 25\% discount. Pam buys 5 tickets using a coupon that gives her a 30\% discount. How many more dollars does Pam pay than Susan?

\mathrm{(A)}\ 2\qquad \mathrm{(B)}\ 5\qquad \mathrm{(C)}\ 10\qquad \mathrm{(D)}\ 15\qquad \mathrm{(E)}\ 20

Full credit goes to MAA for authoring these problems. These problems were taken on the AOPS website.