假设应降价x元,则
(10-x)(30+2x)=272
2(10-x)(15+x)=272
(10-x)(x+15)=136
(x-10)(x+15)+136=0
x²+5x-14=0
(x+7)(x-2)=0
x=2 (x=-7舍)
所以每件应降价2元.