(1)3x-0.5=1.5+2
3x=4
x=4/3
(2)4x-5x+3=5-7x
6x=2
x=1/3
(3)2x-1=3x-1
-x=0
x=0
(4)0.5a+3=4a-4
3.5a=7
a=2