A direct variation equation always takes the form y=kx, where k is a constant
Let's plug in the values of x=6 and y= -3 to solve for the value of k
-3 = k(6)
Let's flip this equality so we have the k on the left side of the equation.
6k = -3
Let's divide both sides by 6
k = -3/6
Now, simplify the fraction
k = -1/2
Now that we found the value of k, our equation is
y = (-1/2) x
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