[tex]7-8x < -x+28\\7-8x < 28-x\\7-28 < 8x - x\\-21 < 7x\\-3 < x[/tex]
(Sorry fo the graph) The idea is the following, draw the straigh line, and put the numbers -3, -2 ,-1, 0, 1, etc. In the position -3 you need to start to draw the interval solution, with an open circle.
[tex](-3, \infty)[/tex]
It is like [tex]\hspace{0.4cm} \circ ----------\\-3 , -2, 0, 1 , 2, ...[/tex]