I think adhesion??
"Adhesion is the attraction of molecules of one kind for molecules of a different kind, and it can be quite strong for water, especially with other molecules bearing positive or negative charges."
Answer: -2/7 or C
Because you have to think rise over run. You move however many you need to (in this case 2) and then over (in this case 7) and then if the line is positive or negative, the answer will be negative or posotive
if x = y then x-y = 0
and then 5 + 2(x-y) = 5 + 2*0 = 5 + 0 = 5
hope this helps