Question

Write the expression in standard form. 3/3-12i

Answer 1

Assuming ya mean $\frac{3}{3-12i}$
and you want complex form as in a+bi 


remember that $i=\sqrt{-1}$ so $i^2=-1$
and remember conguates
we don't want imaginary numbers in the denomenator so

first sipmlify the farction
$\frac{1}{1-4i}$
multiply it by $\frac{1+4i}{1+4i}$
result is
$\frac{1+4i}{(1)^2-(4i)^2}$
$\frac{1+4i}{1-16i^2}$
$\frac{1+4i}{1-16(-1)}$
$\frac{1+4i}{1+16}$
$\frac{1+4i}{17}$
$\frac{1}{17}+\frac{4i}{17}$

in standard form (a+bi form) $\frac{3}{3-12i}$ is
$\frac{1}{17}+\frac{4}{17}i$