let
x-------> the length of the flag
y-------> the width of the flag
we know that
the flag has a rectangular shape
perimeter of rectangle=2*[x+y]
perimeter=28 ft
so
28=2*[x+y]----> divide by 2 both sides----> 14=x+y
x=14-y----> equation 1
if one length is 2 feet more than twice it's width
x=2+2y-----> equation 2
equate equation 1 and equation 2
14-y=2+2y
2y+y=14-2
3y=12
y=12/3
y=4 ft
x=14-y----> x=14-4----> x=10 ft
the answer is
the dimension of the flag is
10 ft x 4 ft