Question 318695
Unfortunately, the first solution is incorrect as the answer does not check.



Let x = original price of the car



Since "It's marked down 10%", this means that the car goes from the original price of 'x' dollars to {{{x-0.1x=0.9x}}} dollars. So after the 10% discount, the car is now 0.9x dollars. Plug in some numbers to help you grasp this.


Now, apply the 20% discount to the new price of 0.9x (not the old price of 'x' dollars) to get {{{0.9x-0.2(0.9x)=0.9x-0.18x=0.72x}}}. So after the 2nd discount of 20% (added on top of the first discount of 10%), the price of the car is now 0.72x



Finally, let's apply the third discount. So after applying the discount of 25% to the second sale price, we get {{{0.72x-0.25(0.72x)=0.72x-0.18x=0.54x}}}


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So after applying all three discounts (in that exact order), the final price of the car is {{{0.54x}}} dollars.



Because we know that the final price is actually $3,240, this means that {{{0.54x=3240}}}. Now just divide both sides by 0.54 to isolate x and get {{{x=3240/0.54=6000}}}



So the solution is {{{x=6000}}} which means that the price of the car was originally $6,000. 


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Check:


Original Price: $6000



After 10% discount, price is now: 6000-0.1*6000 = $5,400



After 20% discount, price is now: 5400-0.2*5400 = $4,320



After 25% discount, price is now: 4320-0.25*4320 = $3,240



So the final price is $3,240 and this confirms our answer.