John and Choon Mui had the same amount of money. When John spent $$$30$$ and Choon Mui spent $$$150$$, John found that the amount he had left was four times as much as the amount of money Choon Mui had left. How much money did John have left? 
Overseas Competition->Knowledge Point->Word Problem Modules->Questions Involving Sum, Difference and Multiples->Problems Involving Sum and Difference