And a linear equation is obtained: [1.3x+1.2× (2000-x) ]× 0.9-2000 = 277.
The equation is as follows: 1. Add 2000 to both sides and divide by 0.9 to get1.3x+1.2 (2000-x) = 2530.
2. Remove the brackets and combine similar items to get 0. 1X= 130.
Thus X= 1300 is obtained, and 2000-X=700 is deduced.
Therefore, the cost of commodity A is 1300 yuan, and the cost of commodity B is 700 yuan.