Consider the following for the two (02) items that follow:
The function f(x) satisfies  $f(x), f \left( \frac{x}{y} \right) = \frac{f(x)}{f(y)}.$  ​for all positive real values of x and y, and f(2) = 3

What is f(1)f(4) equal to?

Consider the following for the two (02) items that follow:

A function f is such that f(xy) = f(x + y) for all real values of x and y, and f(5) = 10

What is f(0) equal to?

Consider the following for the two (02) items that follow:

A function f is such that f(xy) = f(x + y) for all real values of x and y, and f(5) = 10

What is f(20)+f(-20) equal to?

Let z = [y] and y = [x] - x, where [.] is the greatest integer function. If x is not an integer but positive, then what is the value of z?