A store has gift certificates in the amounts of $5, $10, $15, $20 and $50. Sue gave Bill gift certificates from the store that totaled exactly $235. If she used the minimum number of certificates how many $10 certificates did she give Bill?

A) None
B) One
C) Two
D) Three
E) Four

The minimum amount of certificates will be when she uses as many high-value certificates as possible. So she’ll get up to $200 using only $50 certificates, then use a $20 certificate and a $15 certificate. There’s no need to use any $10’s.