Percents — Basic example

- [Voiceover] A pair of jeans that regularly costs $40 is on sale for 30 percent off. As part of a promotion, each customer will also receive an additional discount on the marked sale price at the cash register. If the final price of the jeans was $22.40, what additional discount was applied to the marked sale price? All right, this is interesting and useful, cause we need to know what we're gonna pay for our jeans. All right, so the regular price is $40, we're gonna assume everything is in dollars. It's on sale for 30 percent off. Well if you're 30 percent off that means it's gonna cost 70 percent of the regular price. So let's put 70 percent of 40. So let's multiply that times 0.7, which is the same thing as 70 percent. 40 times 0.7, that's going to be equal to 28, $28. Right? Yeah, seven times four is 28. Point seven times 40 is also going to be 28. All right, so it's going to be $28 would just be the 30% off. But the final price of the jeans was $22.40. What additional discount was applied to the marked sale price? Well to figure that out, we can just divide. We can say, what fraction of 28 is 22.40. 22.40 divided by, divided by 28. Well this is going to be equal to, let's see, 28, and actually you could even rule out, well I'll do the arithmetic right over here. So 28 goes into 22, 22.40, so get the decimal right over here. 28 doesn't go into 22, but it does go into 224. Let's think about it, how many times does 28 goes into 224? I don't know, maybe, maybe seven times? Let's see if this works. So it goes seven times. Seven times eight is 56. Seven times two is 14 plus five is 19. And then if we were to subtract, let's see, we could make this a 14, regroup from here, this would be a one, so then we regroup from here, this would be an 11. 14 minus six is eight, 11 minus nine is two. Okay, so we actually could have gotten one more in there. So let's see, this is going to go, 28 goes into 224 exactly eight times, eight times. Eight times eight is 64, 64. Eight times two is 16 plus six, is 22. No remainder. So this is 80 percent of the marked down price. So if this is 80 percent, if this is 80 percent of this, then the additional discount that was taken is going to be 20 percent. Because you take, once you take 30 percent off, you'd expect to pay $28, but you only paid 80 percent of that. So they took off another 20 percent. They took off another 20 percent. If you take off 20 percent, then you're going to pay 80 percent of the price.