解方程：5x-2=3.6；7（x-1.2）=2.1；7.5×8-4x=20；9.6x-2.4x=21.6；4x-7×1.

5x=3.6+2
5x=5.6
X=1.12
x-1.2=2.1/7
x-1.2=0.3
x=1.2+0.3
X=1.5
60-4x=20
4x=40
x=40/10
X=10
7.2x=21.6
x=21.6/7.2
X=3
4x=9.9+9.1
4x=19
x=19/4
X=4.75