X - 5-X\2 - 12X\4 = 21
4X|4 - 2*(5-X)\4 - 12X\4 = 21
4X -(10-2X) - 12X = 21*4
4X - 10 +2X - 12X = 84
-6X = 94
X = - 15,666 = - 15,7
X - 5-X\2 - 12X\4 = 21
4X|4 - 2*(5-X)\4 - 12X\4 = 21
4X -(10-2X) - 12X = 21*4
4X - 10 +2X - 12X = 84
-6X = 94
X = - 15,666 = - 15,7