tan(pai/4+b)=-3,tan(a+b)=2,tan(pai/4-a)=?

Question

tan(pai/4+b)=-3,tan(a+b)=2,tan(pai/4-a)=?

Answer 1

tan(π/4-a)
=tan[(π/4+b)-(a+b)]
=[tan(π/4+b)-tan(a+b)]/[1+tan(π/4+b)tan(a+b)]
=(-3-2)/[1+(-3)*2]
=1
.