First, add #color(red)(13)# to each side of the inequality to isolate the #w# term while keeping the inequality balanced:
#-4w - 13 + color(red)(13) > 21 + color(red)(13)#
#-4w - 0 > 34#
#-4w > 34#
Next, divide each side of the inequality by #color(blue)(-4)# to solve for #w# while keeping the inequality balanced. However, because we are multiplying or dividing the inequality by a negative number we must reverse the inequality operator:
#(-4w)/color(blue)(-4) color(red)(<) 34/color(blue)(-4)#
#(-color(red)(cancel(color(black)(4)))w)/cancel(color(blue)(-4)) color(red)(<) (17 xx 2)/color(blue)(2 xx -2)#
#w color(red)(<) (17 xx color(blue)(cancel(color(black)(2))))/color(blue)(color(black)(cancel(color(blue)(2))) xx -2)#
#w < -17/2#
To graph this we draw a dashed vertical line at #-17/2#. The line is dashed to indicate the inequality is a "less than" operator and does not include the value #-17/2#. Then you shade to the left of the line to indicated the "less than":
graph{x < -17/2 [-15, 5, -7.5, 7.5]}
