x=78, because |190-210|= -20, then |19-21|= -2 , then the equation will became |-20| + |-2| + x = 100 , if you removed the bar the negative sign will became positive , then the equation will became 20 + 2 + x = 100,add 20 and 2, 22 + x = 100, and transpose 22 to the right side of the equation and it became negative, then the equation will be, x=100-22 and x=78...
