进一退二倍投举例子

简介：The Ming Dynasty was a copper-poor country, with very little copper production each year, and not much tin or lead. Therefore, there was certainly not much bronze mixed with these three metals. Fortunately, Zhu Cihong checked the inner treasury and found out that there were more than 2,000 kilograms of bronze hidden in the inner treasury. If he brought them all, he could cast these ten small cannons.