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