7.8x-2.4x=1.08
5.4x=1.08
x=1.08÷5.4
x=0.2
2x-2.8乘0.5=8.96
2x=8.96+1.4
2x=10.36
x=10.36÷2
x=5.18
2乘（x+1）=6
x+1=6÷2=3
x=3-1
x=2