Joe can buy a game for $50 and sell it for $30, so he is losing $50 - $30 = $<<50-30=20>>20 each month when he buys and sells a game.
Joe starts out with $240 and he buys a game and sells a game he loses $20 per month, so it will take $240/$20 = <<240/20=12>>12 months until he is out of money.
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