5x-2x=9 -3x+0.5x=10
7x-4.5x=2.5*3-5 6x-7=4x-5
x+3x=-16 3x+5=4x+1
9-3x=5x+5 16x-2.5x-7.5x=5
2x+3x+4x=18 13x-15x+x=-3