20:8=x:12 =2.5:5
x-x=15 40%:x=0.2:4.5 25(x+13)=650
31×0.3-0.3x=6 2.4:=3.2:x
= 6x+2×1.5=21
:=:x 0.8:40=x:80 :x = 30:120 =
x:10=4:5 40:x=25:15
1.2x-5.5=0.5 :x=3:16 9x+42=150
+ x=2 8∶x =∶ 50%x-9×3=25