x:=0.5: = 0.2x-1.5=
x-38x=15 40%:x=0.2:4.5 25(x+13)=650
78 + 18x=2 8∶x =13∶116 50%x-9×3=25
3.75:x=3:12 (x-0.6)×310 =2.25 25%:58 =x:49