Boat travels 210mi down and back, takes 10h down and 70h back, how do I set up the problem .. need current and still water speed

This is how you set it up.

c.35

step-by-step explanation:

8+13=21

21+8=29

29+6=35

in the attachment.   i didn't see your choices.   the word which means there is choices.

step-by-step explanation:

(x,y)

x tells you how much left or right you go from the origin

y tells you how much down or up you go from the origin

so for example (-3,2), you go left 3 and up twice. i denoted which of the ordered pairs is which in my graph.