1970 AHSME Problem 19

The sum of an infinite geometric series with common ratio r such that |r|<1, is 15, and the sum of the squares of the terms of this series is 45. The first term of the series is

\textbf{(A) }12\qquad \textbf{(B) }10\qquad \textbf{(C) }5\qquad \textbf{(D) }3\qquad \textbf{(E) }2

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