3X+15-15-2x=2x-15-2x X=-15
19x-76+76+19X=76-19x+76+19X 38X=152 X=4
-9x+7-7+X=-x-1-7+X -8x=-8 x=-1
5x+4+2x-4x-4=4x-5-4x-4 3x=-9 x=-3
0.3x-1.5-x+1.5=x+0.6-x+1.5 -0.7x=2.1 x=3
2/3 y-5+5-2y=2y+3+5-2y -4/3 y=8 两边同时×-3/4 y=-6