Function

f(x) = -x - 3     if x <= 1       see if we can find an answer here

  0 = -x-3

  3 = -x

    x = - 3       this is  <= 1     so this is ONE answer

 

 

Try for the other piece of the piecewise function:

  0 = 1-x/2      for x >1

x/2 = 1

   x = 2       this will work because the 'x' needs ot be >1 for this piece    

 

so the only answer is    x = -3     and  2       summed = -1