Answer
The direct variation equation is $y = 2x$.
$y = 20$
Work Step by Step
The equation for direct variation is given by the following formula:
$y = kx$, where $k$ is the constant of variation.
To write a direct variation equation, we must first find the constant of variation. Let's plug in the values for $x$ and $y$ that we are given:
$8 = k(4)$
Divide both sides by $4$ to solve for $k$:
$k = 2$
The direct variation equation is $y = 2x$.
Now that we have the equation, to find $y$, we simply plug in the value we are given for $x$:
$y = 2(10)$
Multiply to simplify:
$y = 20$
