Question

Express $\frac{15 + 10i}{1 + 2i}$ in rectangular form.

Answer 1

$\dfrac{15 + 10i}{1 + 2i}=\\\\\dfrac{(15 + 10i)(1-2i)}{(1 + 2i)(1-2i)}=\\\\\dfrac{15-30i+10i+20}{1+4}=\\\\\dfrac{35-20i}{5}=\\\\7-4i$