Solution: According to the topic, if X pieces were sold at the price last month, then B sold 1000-x pieces.

It can be listed as (1+50%) x+(1-kloc-0/0%) (1000-x) =1000 (1-4%).

1.5x+900-0.9x =960

900+0.6x =960

0.6x =60

x = 100

1000-x =900

Last month, commodity A sold 100 pieces.

B goods sold 900 pieces.