Answer:
Last option: [tex]12x+28[/tex]
Step-by-step explanation:
The perimeter of a rectangle can be calculated with the following formula:
[tex]P=2l+2w[/tex]
Where "l" is the lenght of the rectangle and "w" is the width of the rectangle.
In this case, you can identify from the figure that:
[tex]l=3x+14\\w=3x[/tex]
Then, you can write the following expression to represent the perimeter of the rectangle:
[tex]2(3x+14)+2(3x)[/tex]
Finally you must simplify the expression; then you get:
[tex]=6x+28+6x=12x+28[/tex]
