ANSWER:
y = 24
EXPLANATION:
Given;
x = 15 when y = 90
Also y varies directly with x
i.e y ∝ x
Introduce a constant k.
y = kx
Let k be the constant.
First solve for K:
[tex]\begin{gathered} y\text{ = kx} \\ \\ 90\text{ = 15k} \\ \text{Divide both sides by 15:} \\ \frac{90}{15}=\frac{15k}{15} \\ 6\text{ = k} \end{gathered}[/tex]Substitute 6 for k in the equation y =kx
Thus, we have:
y = 6x
Therefore, when x = 4, y will be:
[tex]\begin{gathered} y\text{ = 6 }\ast\text{ 4} \\ \\ \text{ y = }24 \end{gathered}[/tex]when x =4, y = 24
