First, add #color(red)(3)# to each side of the inequality to isolate the #x# term while keeping the inequality balanced:
#-12 + color(red)(3) < -4x + (-3) + color(red)(3)#
#-9 < -4x + 0#
#-9 < -4x#
Now, divide each side of the inequality by #color(blue)(-4)# to solve for #x# while keeping the inequality balanced. However, because we are multiplying or dividing an inequality by a negative term we must reverse the inequality:
#(-9)/color(blue)(-4) color(red)(>) (-4x)/color(blue)(-4)#
#9/4 color(red)(>) (color(blue)(cancel(color(black)(-4)))x)/cancel(color(blue)(-4))#
#9/4 color(red)(>) x#
To solve in terms of #x# we can reverse or "flip" the entire inequality:
#x < 9/4#