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