The total area (in sq. unit) of the triangles formed by the graph of 4x + 5y = 40, x-axis, y-axis and x = 5 and y = 4 is:

Answer: Option B

$$\begin{array}{rl}& 4x+5y=40\\ & \Rightarrow \frac{x}{10}+\frac{y}{8}=1\end{array}$$

Intersection point of 4x + 5y = 40 and y = 4 will be,
4x + 5 × 4 = 40
4x = 20
x = 5
∴ Intersecting point is (5, 4)
Area of ΔABC = $$\frac{1}{2}$$ × (10 - 5) × 4 = 10 sq. units
Area of ΔCDE = $$\frac{1}{2}$$ × 5 × (8 - 4) = 10 sq. units
∴ Area bounded by the graph = 10 + 10 = 20 sq units.