Question: Howard spends $8 dollars at the arcade on Monday. On Tuesday, he spends twice as much at the arcade as he did on Monday. On Wednesday, he spends 4 times as much at the arcade as he spent on Tuesday. If he originally had $100, how much money does he have left?
Give me a solution to this problem
Answer: 
On Tuesday, he spends $8 * 2 = $16.
On Wednesday, he spends $16 * 4 = $64.
In total he spent $8 + $16 + $64 = $88 at the arcade.
He has $100 - $88 = $12 left.