0.5x+6=18
0.5x=18-6
x=12÷0.5
x=24
9x+2又1/2=2.5
9x=2.5-2又1/2
9x=0
x=0
0.5+0.25x=2
0.25x=2-0.5
x=1.5÷0.25
x=6
8-4.5x=3又1/2
4.5x=8-3又1/2
4.5x=4.5
x=1
4x-24=2x+20
4x-2x=20+24
2x=44
x=22
2×(x-0.7)=4.8
x-0.7=4.8÷2
x=2.4+0.7
x=3.1
0.7×4-5x=0.8
2.8-5x=0.8
5x=2.8-0.8
x=2/5