Answer:
16 by 9 feet.
Explanation:
We have 50 feet of fencing in total.
Therefore, the perimeter of our area is 50. Perimeter is given by:

Substituting 50 for P yields:

And dividing both sides by 2 yields:

The area of a rectangular is given by:

Where
is the length and
is the width.
We want to enclose 144 feet squared. So, A=144:

By the perimeter equation, we can subtract a variable, say
from both sides. Hence:

Now, we can substitute this into our area equation. Therefore:

Distribute:

Subtract 144 from both sides:

Divide everything by -1:

Factor:

Zero Product Property:

Then it follows that:

Or:

Regardless, the dimensions of the rectangular area will be 16 by 9 feet.