Answer:
The point at which the banner should be attached to the archway is going to be given by the point(s) at which the two equations intercept:
y = -x^2 + 6x and 4y = 21 − x
Solving the system of equations, we find that they intercept at: (1, 5) and (5.25, 3.938)
Therefore, the banner should be attached to the archway at the points (1, 5) and (5.25, 3.938)
By observing the graph we can note down the following things about the boundary line:
Let's look at the shaded region. The origin lies inside it.
Thus, the point $(0,0)$ satisfies the equation of the region.
Upon putting it in the options, we find that only two options: 2 and 4 satisfy the inequality $0<5$
Now find the Y-intercept of the boundary line:
Option 4) $0-2y=5$
$y=\frac{-5}{2}<-2$
Since it is smaller than -2, it is the wrong option.
Hence, correct option is $\boxed{x-3y<5}$