2X-1.8=X+2.4
2x-x=2.4+1.8
x=4.2
3X-2(10-X)=15
3x-20+2x=15
5x=35
x=7
(2X+3)*2=5X-4
4x+6=5x-4
5x-4x=6+4
x=10
18/4X-3=9
18/4x=12
x=8/3
(4-X)*7=(X-4)*9
28-7x=9x-36
9x+7x=28+36
16x=64
x=4
6.2*(3X-4)+7*(4-X)=4X
18.6x-24.8+28-7x=4x
18.6x-7x-4x=24.8-28
7.6x=-3.2
x=-8/19