In inverse proportion. According to the query of Zhonggong Education Network, when LAC is in the decline stage, LAC is greater than LMC and Ec is less than 1, the return to scale will increase, realizing economies of scale. When lac is in the rising stage, LAC is less than LMC, Ec is greater than 1, and the returns to scale decrease, which means that LAC curve is inversely proportional to the returns to scale. Scale reward refers to the change of output when various production factors in an enterprise change in the same proportion under other conditions unchanged.