A particle is moving along the curve whose equation is
$$
\frac{x y^{3}}{1+y^{2}}=\frac{8}{5}
$$
Assume that the $x$ -coordinate is increasing at the rate of 6 units/s when the particle is at the point $(1,2) .$
(a) At what rate is the $y$ -coordinate of the point changing at that instant?
(b) Is the particle rising or falling at that instant?