Question 1012092
If A is the angle between two lines whose slopes are m1 and m2 then
   
   Given A = arctan {{{2/3}}}, so {{{TanA = 2/3; m1= -1}}}

  Tan A = {{{(m1 - m2)/ (1+ m1m2) = 2/3}}}
  
        = {{{(-1 - m2)/ (1 +(-1)*m2)= 2/3}}}
          {{{ -3 - 3 m2 = 2 - 2 m2}}}   (Cross multiplying)
            {{{3 m2 - 2m2 = m2 = -2 - 3 = -5}}}
          Therefore the slope of line n = -5