The price of a digital camera sold in stores is $129. It is sold on eBay for $65. What is the percent decrease from the store's price to the online price

what i did is multiply 65 times 100, and divided by 129,  (65)(100)= 6500 6500/129= 50.3 then to check i did multiply 50.3 by 129, and divided by 100 (50)(129)= 6450 6450/100= 64.50  I don't think its 50% or either 51%, because 50% gives something less than 65, and 51% gives more than 65. So maybe its in the middle. to get the right percentage do 50.1 or 5.6 times 129, and then divide by 100