AHSME 1968 Problem 19

Let $n$ be the number of ways $10$ dollars can be changed into dimes and quarters, with at least one of each coin being used. Then $n$ equals: $\text{(A) } 40 \text{(B) } 38 \text{(C) } 21 \text{(D) } 20 \text{(E) } 19$