(20.5-5.5)/(2.3-1.3)=1515*2.3+5.5=40答案是40米
设做上衣n件,则:2.3*n+5.5=1.3*n+20.5n=15总共2.3*15+5.5=40米
(20.5-5.5)/(2.3-1.3)=1515*2.3+5.5=40答案40米