Question: A company bought $400000 worth of equipment from a retailer business, but pieces of equipment worth 40% of the total number were faulty. If they returned the faulty pieces of equipment to the seller, calculate the total amount of money spent on functioning pieces of equipment.
Give me a detailed solution. 
Answer: 
If 40% worth of the pieces of equipment bought were faulty and were returned, the amount of money they were bought for is 40/100*$400000 = $160000
Since the faulty pieces of equipment were worth $400000, the functioning equipment was worth $400000-$160000 = $240000