Answer:
L=78 feet W=27 feet
Explanation:
lets call the width w and length l.
2(w+4w-30)=210 (the bracket is multiplied by 2 because there are 2 lengths and widths)
5w-30=210
divide both sides of the equation by 2 to eliminate the brackets
5w-30=210/2
5w-30=105
add 30 to each side
5w=105+30
5w=135
w= 135/5 = 27
L=27x4-30
L=78