When solving inequalities, treat like an ordinary algebra problem, then worry about how to graph it. 
Don't forget to change signs if you have to divide or multiply by a negative number (such as -5 > -x > -15, which then becomes 5 < x < 15, in this equation X is between 5 and 15, open ended circles at those points (5 and 15), solid line inbetween. 
2x + 3 > y
or if it helps to look at it with the Y first:
y < 2x + 3
1)  Plug in values for X to obtain values HIGHER than Y
2) (0, <3) - NOTE, at the y < 3, put an open circle at the 3 and put a vertical line below since ALL numbers below THREE satisfy the equation.
3) (1, <5), again, at X = 1, an open circle at the 5 and vertical line below. 
4)  Connect the points for the line using dotted lines (because Y does NOT equal 3 or 5), A SOLID LINE REPRESENTS "EQUAL TO". 
5)  Graph will be a dotted line with all values underneath the "line" included. 
if (isMyPost) { }