解比，数学六年级。

0.3:2X=1:6

2X=1.8

X=0.9

50-X/4 = 0 .8:1/2

25-X/2=3.2

X/2=25-3.2

X=43.6

49:(10—X)=14:2

140-14X=98

14X=42

X=3

1/15:1/5 = 1/X:1/3

15/5=X/3

X=9