Andy has $240. He had twice as much money as Carl. Carl spent some money and Andy had 6 times as much money as Carl in the end. How much did Carl spend?

Carl must have started with $120

So

6 (120 - S) = 240

720 - 6S = 240

720 - 240 = 6S

480 = 6S

480 / 6 = 80 ......Carl spent $80

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