If x varies y and x =20 when y=8 fine the formular connecting x and y x when y=7 y when x=10

Answer 1

"x varies y" is gibberish. I assume you meant that "x varies directly as y"
x = ky
20 = 8k, so k = 5/2
x = 5/2 y
Now use that to answer the other questions

Or, if you meant that "x varies inversely as y"
then xy = k and k = 160