A math problem The price of a commodity is 900 yuan. In order to participate in the market competition, the store will sell it at a 10% discount, and then give it to 40 yuan, and you will have a profit of 10%. 900× 90% = 8 10 (yuan): the purchase price of this commodity is X yuan.

8 10-40=770 yuan (1+10%) x = 900 * 0.9-40.

770 ÷ (1+ 10%) = 700 (yuan)1.1x = 810-40.

1. 1X=770

X=700

The purchase price of this commodity is 700 yuan.