一、内项积等于外项积形式 270 : 120 = 0.9 :x 34 : 1.2 = 50% :x 解:270x=120×0.9 解:34x =1.2×50% 270x=108 34x =35 x=0.4 x =45 二、分子、分母交叉相乘积相等形式 140.35 = 120x x1−10% = 34 解:14x=0.35×120 解:4x =3×(1-10%) 14x=42 4x =2.7 x=3 x =0.675 三、比号式或分数式先统一形式,再相乘 38 : 12 = x240 40−x4 = 0.8 :15 解:38 : 12 = x : 240 解:(40-x) : 4= 0.8 :15 12x=38 ×240 15 (40-x)=4×0.8 12x=90 8- 15x=3.2 x=7.5 x=24
