Inverse variation formula is y = k/x
To find k you would multiply by x on both sides.
So..xy = k
Since k is a CONSTANT we need to multiply xy and get the same number (k).
This only happens with the last choice. Each pair of numbers yields, 60.
2*30 = 60; 3*20 = 60, 4*15 = 60; 5*12 = 60
