#sin(x+y)/cos(x-y)-2tan(x-y)#
#=sin(x+y)/cos(x-y)-(2sin(x-y))/cos(x-y)#
#=(sinxcosy+cosxsiny-2sinxcosy+2cosxsiny)/cos(x-y)#
#=(3cosxsiny-sinxcosy)/(cosxcosy+sinxsiny)#
#=((3cosxsiny)/(cosxcosy) -(sinxcosy)/ (cosxcosy) )/((cosxcosy)/ (cosxcosy )+(sinxsiny) /( cosxcosy) #
#=(3tany-tanx)/(1+tanxtany)#