Answer:

Step-by-step explanation:
The formula that is used to calculate the area of a rectangle is:

Where "l" is the lenght and "w" is the width.
You know that the area of that rectangle is:

And, according to the exercise, its lenght is 7 more than its width; then:

Then, you can make the corresponding substitution into the formula
:

Simplify:

Factor the equation. Find two numbers whose sum is 7 and whose product is -744. These are 31 and -24.
Then, you get:

The width of the rectangle is the positive value:

Then, the lenght is:

All you do is 2.5 times the number of feet so 2.5x , x is the number of feet
Cross-multiply:
7 * 3 = 5 * x
Divide each side by 5 :
X = 7 * 3 / 5 = 4.2
South west
Shifting 4 units left (decreasing in x-axis by 4 units)
Shifting 5 units down (decreasing in y-axis by 5 units)
Apply to every vertices coordinates(x - 4, y - 5)
New coordinates
A(-2, -1)
B(-1, -4)
C(1,0)