Answer
$41-13i$
Work Step by Step
Note: the standard form of a complex number is $a+bi$ where $i = \sqrt -1$ and $a$ and $b$ are real numbers.
Note: $i^{2} = \sqrt -1\sqrt -1 = -1$
$(7+5i)(3-4i)$
First, expand out the complex number:
$21-28i+15i-20i^{2}$
As seen in the note above, $i^{2} = -1$, so substitute in $-1$.
$21-28i+15i-20(-1)$
$21-28i+15i+20$
Combine like terms, to express the complex number in standard form:
$41-13i$
