Lisa has 45 coins, which are worth a total of $3.50. If the coins are

Lisa has 45 coins, which are worth a total of $3.50. If the coins are all nickels and dimes, what is the difference between the number of dimes and the number of nickels? (A) 5 (B) 10 (C) 15 (D) 20 (E) 25 Source: Master GMAT