设这批零件共X个。第一天加工1/4X+7个;第二天加工2/5(X-1/4X+7)+2个。剩余5/18X个零件没加工。可得下列不等式:1/4X+7+2/5(X-1/4X+7)+2=5/18X解得X=36所以这批零件共36个。