The circumference of this circle is Px (because circumference = Pd). In order to convert that value to kilometers, you will need to divide by 1,000. So, the circumference = (Px) / 1000. Now you need to find the number of revolutions. You do this by figuring out how many of the circumference lengths fit into the distance travelled. You do that by dividing:
y / [(Px) / 1000]
= (y * 1000) / (Px)
= 1000 y / P x
(A)