Lucy bought a microwave oven at 10% off the original price. If she paid $21, what was the original price of the microwave?

Question

Avery Alexander · Accepted Answer

The original price was $23.33

We can write this formula to solve this problem as: #x - (10%# of #x) = $21# "Percent" or "%" means "out of 100" or "per 100", Therefore 10% can be written as #10/100#. When dealing with percents the word "of" means "times" or "to multiply". So we can rewrite this equation as: #x - (10/100 xx x) = $21# #x - 10/100x = $21# #(100/100 xx x) - 10/100x = $21# #100/100x - 10/100x = $21# #(100 - 10)/100x = $21# #90/100x = $21# #color(red)(100)/color(blue)(90) xx 90/100x = color(red)(100)/color(blue)(90) xx $21# #cancel(color(red)(100))/cancel(color(blue)(90)) xx color(blue)(cancel(color(black)(90)))/color(red)(cancel(color(black)(100)))x = color(red)($2100)/color(blue)(90)# #x = $23.33#

Julia Adams · Answer

undefined To find the original price of the microwave oven, divide the discounted price by (1 - discount rate).

Original price = Discounted price / (1 - discount rate)
Original price = $21 / (1 - 0.10)
Original price = $21 / 0.90
Original price = $23.33

So, the original price of the microwave oven was $23.33.