The Area of a rectangle can be calculated by using the formula:
[tex]A=L\times W[/tex]Where A is the area, L is the length and W is the width.
By replacing the given values, your equation will be:
[tex]15ft^2=y\times3ft[/tex]Do the next steps to find the value of y:
[tex]\begin{gathered} \text{Divide both sides by 3 ft} \\ \frac{15ft^2}{3ft}=y\times\frac{3ft}{3ft}\text{ } \\ \text{Simplify and reorder terms} \\ 5ft=y \\ y=5ft \end{gathered}[/tex]Thus, the value of y is 5 ft.