Answer
variation constant $=k=5$
equation: $y=5x$
Work Step by Step
RECALL:
When $y$ varies directly as $x$, the equation that represents the variation is of the form $y=kx$ where $k$ is the constant of variation.
Find the constant of variation by substituting the given values into the equation $y=kx$ to obtain:
$$y=kx
\\80=k(16)
\\\frac{80}{16}=\frac{k(16)}{16}
\\5=k$$
Thus, the equation of the direct variation is:
$$y=5x$$
