A sign says that the price marked on all music equipment is at a discount for 30% off. You buy an electric guitar for the same p
rice of $315. {Im only in 7th grade.}
What is the percent you pay? _____________
Write an equation to find the regular price of the item. __________________
What was the regular price? ____________
a. So the electric guitar is sold for a sale price of $315 after the discount. The discount was 30%. Even though we get that amount off, we still pay 70% of the original price, because 100% (original price) - 30% is 70%.
b. An equation that can help us find the regular price of the item is through writing and solving a proportion. Set it up like this:
315/x = 70/100
This is because 315 is part of the whole and is 70% of the value of x.
How to solve it:
Okay. Let's solve this by cross multiplying the values. 315 * 100 is 31,500. 70 * x is 70x. That simplifies to 31,500 = 70x. Didivde each side by 70 to isolate the x. 70x/70 cancels out. 31,500/70 is 450. Let's check this by multiply the number by 70% and see what happens. 450 * 70% (0.7) is 315. There. x = 450. The regular price was $450.
I am not going to tell you the answer but to find the part you have to make the percent a decimal like .30 and then multiply it by the whole which is 315 and then you get the part. So now that you've got the part you can add or subtract it by the whole it depends on what the question is asking you if it is asking you what it was before it was 30% off then you have to add the part to find it if it is asking you what it was after... you get it. Now solve it yourself. ;)
