Answer:
Step-by-step explanation:
There are additional details to the problem that you have left out. I have found them in other resources. The tray has to be 3 centimeters high and the length is five centimeters longer than its width. The volume of the tray is 252 cubic centimeters.
With these given, we can find the equation with the width alone as the variable:



To know if it's possible for the width to be 7.5 centimeters, we just plug this as the value of x and see if it satisfies the equation:



As we can see, the equation was not satisfied therefore it is NOT possible for the width to be 7.5 centimeters.
Answer:
A) The coordinates of the fourth vertex are:
1) x-coordinate:

2) y-coordinate:

B) The point of intersection of the diagonals is: 
Step-by-step explanation:
We need to remember that the diagonals of a parallelogram intersect each other at a half-way point and the midpoint of each diagonal is the same.
The midpoint formula is:

Since:

We can find the coordinates of the fourth vertex
through these procedure:
1) x-coordinate:

2) y-coordinate:

Therefore, fourth vertex is
Since the point of intersection of the diagonals is the midpoint of a diagonal (Remember that
), this is:

Therefore, the point of intersection of the diagonals is 