2)
(3-7i)/(3+4i)
=(3-7i)(3-4i)/(3+4i)(3-4i)
=(9-12i-21i+28i²)/(3²-4²*i²)
=(9-33i-28)/(9+16)
=(-19-33i)/25
3)
x/y=6/5i
=6i/(5i²)
=6i/(-5)
