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?
Jill's second customer buys 4 times more than her first customer's 5 boxes, so they buy 4*5=20 boxes
Jill's third customer buys half of what her second customer bought, so that means they buy 20/2= 10 boxes
Jill's fourth customer buys 3 times as many as what her third customer bought, so that means they buy 10*3= 30 boxes
Adding in the 5 boxes sold to the first customer, and the 10 boxes sold to the last one, that means Jill has sold 5+10+20+10+30= 75 boxes
Since Jill's goal is 150 boxes sold, and she's only sold 75 so far, she needs to sell 150-75=75 more boxes to hit her goal