Question 991365
Start with a right triangle. 
Form similar triangles with height 10 and height 6.
The horizontal distance from the light to the man is {{{a}}}.
The horizontal distance from the man to the tip of the shadow is {{{b}}}.
So then,
{{{10/6=(a+b)/b}}}
{{{10b=6a+6b}}}
{{{4b=6a}}}
{{{2b=3a}}}
{{{2(db/dt)=3(da/dt)}}}
{{{2(2)=3(da/dt)}}}
{{{da/dt=4/3}}}{{{fps}}}