Question 5388: An instrument store gives a 10% discount to all students off the original cost of an instrument. During a back to school sale an additional 15% is taken off the discounted price. Julie, a student at the local high school, purchases a flute for $306. How much did it originally cost? I solved this question and i got $408 but they say that it isn't correct.
Answer by Abbey(339)   (Show Source):
You can put this solution on YOUR website! Let x = original cost
Let .90x = the amount the student pays (100%-10% = 90%)
Let .85(.90x) = the sales price (100%-15%=85%)
If the sales price = 306, then
.85(.90x)=306
.765x=306
x=$400
So the original cost was $400
This makes sense because $40 was taken off for the student discount, bringing the sales price to $360 and an additional 15% of 360 = $54, so $360-$54 = $306
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