Answer with explanation:

Cost of a Pencil = $ 0.25

Cost of a Eraser = $ 0.50

⇒Total Amount Spent on Pencil and Eraser < 3.

⇒Cost of x Pencil +Cost of y Eraser < 3

⇒ 0.25 x + 0.50 y < 3

Rightarrow frac{25 x}{100}+frac{50y}{100}< 3\\Rightarrow 2 5 x +50 y < 300\\Rightarrow x +2 y < 12\\Rightarrow frac{x}{12}+frac{2y}{12}<1\\Rightarrow frac{x}{12}+frac{y}{6}<1

⇒Put, x=0 and y=0,to know which side of the graph you have to shade.

0+0< 12⇒0< 12

Shade that part under line,  which contains origin.