Question

y varies directly with x. y is -3 when x is -9. what is y when x is 48? y = ?

Explanation:

Step1: Find the constant of variation

Since $y$ varies directly with $x$, the equation is $y = kx$. Substitute $x=-9$ and $y = - 3$ into the equation: $-3=k\times(-9)$. Solving for $k$, we get $k=\frac{-3}{-9}=\frac{1}{3}$.

Step2: Find $y$ when $x = 48$

Substitute $k=\frac{1}{3}$ and $x = 48$ into $y=kx$. So $y=\frac{1}{3}\times48 = 16$.

Answer:

$16$