(a).

The cost function is ,where .

Graph :

Draw the coordinate plane.

Graph the function .

(b).

Now plot the graph at to find the intersection of graph with .

Graph :

Graph the function ,at to find the point of intersection.

Observe the graph :

The line intersects the garph at .

Therefore of salt is removed by spending per day.

(c).

No, The function is not defined when .

This represents that it is not financially feasible to remove of the salt at the plant.

(a).

Graph of the function is

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(b). of salt is removed by spending per day.

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(c).  No, it is not financially feasible to remove of the salt at the plant.