Answer:
x = 3 feet
Step-by-step explanation:
Perimeter of a rectangle = 2 x ( length + width)
Perimeter = 6x + 14
length = 3x
width = 2x + 1
Substitute the dimensions in the equation for the perimeter of a rectangle
2 (3x + 2x + 1) = 6x + 14
Divide both sides of the equation by 2
3x + 2x + 1 = 3x + 7
5x + 1 = 3x + 7
Collect like terms
2x = 6
divide both sides by 2
x = 3