4x - 9 * (x - 7) = -12
4х - 9х + 63 = -12
-5х = -63 - 12
-5х = -75
х = 15
15(-3-(19-18x))+3x=x+90+2x
раскроем скобки
-45-285+270x+3x = x+90+2x
270x-420 = 0
270x = 420
x = 420/240
х=1,75
4x - 9 * (x - 7) = -12
4х - 9х + 63 = -12
-5х = -63 - 12
-5х = -75
х = 15
15(-3-(19-18x))+3x=x+90+2x
раскроем скобки
-45-285+270x+3x = x+90+2x
270x-420 = 0
270x = 420
x = 420/240
х=1,75