John has to replace the ball bearings for machines he works with. He has 10 machines and they take 30 ball bearings each. It normally costs $1 per ball bearing but right now there is a sale where they are only $.75. Also since he is buying in bulk he gets a further 20% discount. How much money did he save by buying them all during the sale rather than 1 at a time? Let's be accurate as possible.
He needs to replace 30 * 10 = 300 ball bearings. The normal price is 300 * 1 = $300. Because of the sale he only has to pay 300 * .75 = $225. He then gets a discount which shaves another 225 * .2 = $45 off the price. That means he only pays 225 - 45 = $180. So he saved 300 - 180 = $120.
The answer: 120.