5-x=4(x-3)
7-(2x+3)=9
1/2(x-4)+3x=5

а)5-x=4(x-3)5-x=4x-12-x-4x=-12-5-5x=-17-x=-3,4x=3,4б)7-(2x+3)=97-2x-3=9-2x=9-7+3-2x=5x=-2,5в)1/2(x-4)+3x=51/2x- 2+3x=53,5x=5+23,5x=7x=2