5) 5*(х-2.8)=3*(2х-1.8)

5х-14=6х-5.4

х=-8.6

6) 9х-8=5х

4х=8; х=2

7) 9х+24*15=4х+240

5х=-120; х=-120/5; х=-24

8) 2х/9-1/3=4х+5/2

4х-6=18*4х+5*9

-6-45=68х

х=-51/68

х=-3/4