I know D is correct but idk about the rest

Alogical argument that is presented in graphical form using boxes and arrows is called?

If y varies directly as x2 and y=6 when x=6, find the constant of variation.

Jonathan can type 20 documents in 40 minutes ,and susan can type it in 30 minutes and jack can type it in 24 minutes working together ,how much time will it is take them type the same document