For items 11-15, write True if the statement is true; otherwise, write False.
11. In the linear inequalities ax + by <c, either a or b can be zero.
12. The boundary line of y> 3x + 5 is a solid line.
13. The boundary line of 2x + 3y 2 is a broken line.
14. The shaded half-plane of the graph of y< 6x + 4 is the upper half plane.
15. The shaded half-plane of the graph of y 2 -2x + /2 is the lower half-plane.​