A 5.5 foot man walks away from a 12 fokt lampost at a constant speed. At a given moment, let l be the length of the man's shadow (along the ground) and ket x be his distance from the lampost.
Sketch a figure that represents the problem
Express l in terms of x
did you do the sketch? It should be clear that
l/5.5 = (x+l)/12
no crank it out. Algebra I, babe.