The mathematical expressions to be implemented include

The mathematical expressions to be implemented include:

a. Slope of a line given two points (m = (y2-y1)/(x2-x1)

b. average for an undetermined number of input integers (avg = (x1+x2 + x3 + x4 ... +xn)/n

c. Simple interest (Interest = Principle * Rate * time in years)

d. Area of a rectangle (area = length * width)

e. Your mathematical formula

The script should use good design techniques including an easy-to-use interface, separation of functionality and be tested rigorously for logic and other errors.