(1+sinθcosθ-cosθ^2)/(cosθ^2-sinθ^2)
=(sinθ^2+sinθcosθ)/(cosθ+sinθ)(cosθ-sinθ)
=sinθ(sinθ+cosθ)/(cosθ+sinθ)(cosθ-sinθ)
=sinθ/(cosθ-sinθ)
=2
∴2cosθ-2sinθ=sinθ
2cosθ=3sinθ
tanθ=2/3
tan(π/4-θ)
=(tanπ/4-tanθ)/(1+tanπ/4tanθ)
=(1-2/3)/(1+2/3)
=1/5