The price of an item has been reduced by 80%. the original price was $45. what is the price of the item now?

%change=100(final-initial)/initial, so we can say:

100(final-45)/45=-80  multiply both sides by 45

100(final-45)=-3600  divide both sides by 100

final-45=-36  add 45 to both sides

final=9

So the price of the item now is $9.