Answer:
12 feet.
Explanation:
we are given some information about the length and width of a rectangle.
first, let w be width and l be length.
we have the system of equations:

we substitute the expression for l into the 2nd equation: 3w - w = 8.
this simplifies to 2w = 8 and dividing both sides gives w = 4.
since length is triple the width, we have length = 12 feet.