A point π P π is moving along the curve whose equation is π y=9x π. How fast is the distance between π P π and the point π (4,36) π if π x π is decreasing at the rate of π 7 π unitss at that instant?
a) π 6√5 π unitss
b) π 7√5 π unitss
c) π 8√5 π unitss
d) π 9√5 π unitss