Convert to Trigonometric forms first
#-3+6i=3sqrt5[cos(tan^-1((6)/(-3)))+i sin(tan^-1((6)/(-3)))]#
#-4+7i=sqrt65[cos(tan^-1((7)/(-4)))+i sin(tan^-1((7)/(-4)))]#
Divide equals by equals
#(-3+6i)/(-4+7i)=#
#(sqrt45/sqrt65)[cos(tan^-1((6)/(-3))-tan^-1((7)/(-4)))+i sin(tan^-1((6)/(-3))-tan^-1((7)/(-4)))]#
Take note of the formula:
#tan (A-B)=(Tan A-Tan B)/(1+Tan A* Tan B)#
also
#A-B=Tan^-1 ((Tan A-Tan B)/(1+Tan A* Tan B))#
#(3sqrt(13))/13[cos(tan^-1((-1)/18))+i*sin(tan^-1((-1)/18))]#
#(3sqrt(13))/13[cos(6.2276868019339)+i*sin(6.2276868019339)]" "#radian angles
#(3sqrt(13))/13[cos(356.82016988014^@)+i*sin(356.82016988014^@)]" "#