Answer
$y=2.5x;30$
Work Step by Step
start with the function form of a direct variation
$y=kx$
now substitute 3 for x and $7\frac{1}{2}$ for y (we will use 7.5)
$7.5=k(2)$
divide both sides by 3 and solve for $k$
$\frac{7.5}{3}=\frac{k(3)}{3}$
$k=2.5$
write an equation and substitute 2.5 for k.
$y=2.5x$
Now solve for x=12
$y=2.5(12)$
$y=30$
