急解答一道英文数学题.

题目

急解答一道英文数学题.
4 carpenters each built an average of 42 chairs last week,If no chairs were left uncompeleted and if P ,who built 50 chairs,built the greatest number of chairs,what is the least number of chairs one of the carpenter could have built,if no carpenter built a fractional number of chairs?

答案

题目是这样的:四个木匠上星期做椅子,平均没人做42张.其中,P是做的最多的50张,那么做的最少的是多少张呢?椅子数都为整数.
解法:另外两个人也做最多时即49,则最后一个做的最少为42*4-50-49*2=20