Answer
increases;
decreases
Work Step by Step
When $y$ varies directly as $x$, then $y=kx$ where $k$ is the constant of variation.
Note that if $k\gt 0$, when the value of $x$ increases, the value of $y$ also increases. When the value of $x$ decreases, the value of $y$ also increases.
Thus, the missing expressions in the given statement (in order) are:
increases;
decreases
