#### Answer

$\displaystyle \frac{increase~in~salary~(part)}{last~year's~salary~(whole)}=\frac{percent~increase~(unknown)}{100}$

#### Work Step by Step

To figure out the salary percent increase, we would set up the fraction like so:
$\displaystyle \frac{increase~in~salary}{last~year's~salary}=\frac{percent~increase}{100}$
increase in salary: the "part" (difference between this year's salary and last year's salary).
last year's salary: the "whole" that we divide by.
percent increase: right side numerator (our unknown).
We would then cross-multiply and solve the for unknown (percent increase).