Which formula shows a joint variation?

The answer is the first option: I, II and III.

The explanation is shown below:

1. By definition, there is a joint variation  when a variable depends on two or more different variables. Therefore, you can express it as following:

Where and are the variables and is the constant of proportionality.

As you can see, is directly proportional to and .

2. Keeping the information above, you have:

I) ( varies jointly with , and .

II) (If is the constant of proportionality, varies jointly with and ).

III) ( varies jointly with and .

a 270° rotation about point p says on e d g e n u it y (had to space it out because it says it's a misspelling so i couldn't submit it