Inverse variation is of the form y=k/x, or if you prefer yx=k. "Inverse" variation because as x increases, y decreases...Anyway the equation can be expressed as:
y=k/x, we are given one point (10,8) so we can find the value of k, the constant of variation using those coordinates...
8=k/10 multiply both sides by 10
80=k so the equation is:
y=80/x