WAEC Mathematics 2010 Paper

Concept:The graph shows the boundary line $x+y=3$, and the shaded region represents the set of points satisfying one inequality.Explanation:The line cuts the $x$-axis at $(3,0)$ and the $y$-axis at $(0,3)$.So the equation of the boundary line in intercept form is:$$\frac{x}{3}+\frac{y}{3}=1$$Multiplying through by $3$ gives:$$x+y=3$$From the diagram, the shaded portion lies below this line.Also, the boundary line itself is not shaded.Hence, the shaded portion satisfies:$$x+y<3$$Answer:Option B: $x+y<3$