2.4x+2.4=6.8-2x
2.4x+2x=6.8-2.4
4.4x=4.4
x=1
5分之2x+4=12-2（x-2)
0.4x+4=12-2x+4
0.4x=12-2x
2x+0.4x=12
2.4x=12
x=5