2X+4（8-X）=20
2x+32-4x=20
-2x+12=0
x=6
10X-6（10-X）=36
10x-60+6x=36
16x=96
x=6
10X-6（16-X）=64
10x-96+6x=64
16x=160
x=10
0.5X+0.1（8-X）=2
0.5x+0.8-0.1x=2
0.4x=1.2
x=3
4X-2（8-X）=14
4x-16+2x=14
2x=30
x=15