Answer
$y = 60$
Work Step by Step
First, we need to find the constant of variation for this exercise. We have an $x$ value and a $y$ value. Let's plug these values into the formula for direct variation, $y = kx$ to find $k$, the constant of variation:
$$15 = k(3)$$
Divide both sides by $3$ to isolate $k$:
$$k = 5$$
The constant of variation is $5$.
To find $y$ when $x$ is a specific value, plug $x$ and the $k$ into the formula for direct variation:
$$y = 5(12)$$
Multiply to simplify:
$$y = 60$$
