By definition, the area is given by:
A = w * l
Where,
w: width
l: length
We have two expressions for the length:
L = 14\\L = 5 + 3c
Since the length is the same, we equate both expressions:
5 + 3c = 14
From here, we clear the value of c:
3c = 14 - 5\\3c = 9
c = \frac{9}{3}\\c = 3
Then, we have that the width is given by:
W = 6c-8
Substituting the value of c we have:
W = 6 (3) -8\\W = 18-8\\W = 10
Finally, the area is given by:
A = w * l\\A = 10 * 14\\A = 140 ft ^ 2
Answer:
he should order 140 square feet