A salted fishapos;s

"I heard some whispers before coming here, saying there were blue bricks and red bricks. I wonder what their prices are",Qing bricks cost one copper coin each, and red bricks cost one copper coin each.,The old man said, "It depends on how many houses you want to build. Six houses would cost about 40,000, three houses around 20,000. How many houses are you planning to build"。