There's A Lighttt....

This is the Image

Finding the equation of x and y

$\frac { 5 }{ y } =\frac { x+4 }{ x } \quad$ thus $\quad x=\frac { 4y }{ 5-y }$

Derivating x regarding to time using quotient rule

$\frac { dx }{ dt } =\left( \frac { 4 }{ 5-y } +\frac { 4y }{ { (5-y) }^{ 2 } } \right) \frac { dy }{ dt }$

Thus at the moment when $y=2$ m and $\frac { dy }{ dt } =9m/sec$

$\frac { dx }{ dt } =\left( \frac { 4 }{ 5-2 } +\frac { 4.2 }{ { (5-) }^{ 2 } } \right) .(-9)=-20m/sec$

The shadow of the ball is moving at a speed of -20 m/sec at this moment