Explanation
We are told that the perimeter of a rectangular poster is 14 feet and the length is 4 feet.
Perimeter simply means the total sum of all the sides of the rectangle
[tex]\begin{gathered} From\text{ the above} \\ let\text{ the length = y} \\ width\text{ =x} \end{gathered}[/tex]
So, the perimeter is
[tex]x+x+y+y=2x+2y[/tex]
Since the perimeter is 14 then
[tex]2x+2y=14[/tex]
Also, the length is 4 feet
Therefore y = 4, so that
[tex]\begin{gathered} 2x+2(4)=14 \\ 2x+8=14 \\ collecting\text{ like terms} \\ 2x=14-8 \\ 2x=6 \end{gathered}[/tex]
Making x the subject of the formula
[tex]\begin{gathered} x=\frac{6}{2}=3 \\ \\ x=3 \end{gathered}[/tex]
Therefore, the width of the rectangle is 3 feet
The rectangle is
[tex]4+3+4+3=14[/tex]
