I need a clearer understanding of how to solve: Jill sells girl scout cookies.  This year, she wants to sell at least 150 cookie boxes.  Her first customer buys 5 boxes,  Her second one buys 4 times more than her first customer.  Her third customer buys half as much as her second.  The fourth customer buys 3 times as much as her third.  Lastly, her final customer buys 10.  How many boxes so Jill have left to sell to hit her sales goal?