Then he told Yan Lao Er, "I'll calculate half the amount for you first. When you return from the quarry, tell me the exact number.",“Why aren’t you expensive A hundred catties for just three coins, and once winter arrives, they will sell for five coins.” The old man sighed: “Don’t think my bricks are expensive either; my family only earns a hard-earned living.”,He pulled out another thin slate and showed it to everyone: "There are also these kinds. The foreman at the quarry said that these slates can be used for heating floors."。