Math equation

stationery store selling two is priced at 120 yuan and 80 yuan commemorative coins, two coins each with 30% of the profits, priced at 120 yuan a good sale, A total of 1080 RMB money, want to buy a certain number of commemorative coins, if the price to buy 120 yuan in enough money, but the salesman was shown with this commemorative coins to pay him a result, profit and sell the same amount of stationery is priced at 80 yuan profit in the same coin much, a total number of commemorative coins to buy?

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Solution: Let x Xiao Ming bought a commemorative coin, then the money payable to the salesperson for the 120x,

profit of 120x × 30%, poor money to 120x-1080

120x × 30% -- (120x-1080)

∵ stationery store and sell the same amount of profit for each 80 coin profit of as much as

∴ 80x × 30% = 120x × 30% - (120x-1080)

24x = 36x - 120x +1080

24x-36x +120 x = 1080

108x = 1080

x = 10

A: Xiao-Ming bought a total of 10 commemorative coins.