2012 Fermat Problem 6

John ate a total of 120 peanuts over four consecutive nights. Each night he ate 6 more peanuts than the night before. How many peanuts did he eat on the fourth night?

\textbf{(A)}\ 42\quad \textbf{(B)}\ 39\quad \textbf{(C)}\ 30\quad \textbf{(D)}\ 36\quad \textbf{(E)}\ 33

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