Answer:
33% of the grid is not shaded.
67% of the grid is shaded.
67/100 of the grid is shaded.
Multiply the first equation by 2
-6x + 4y = -78
5x + 4y = 21
Subtract those two equations
-11x = -99
X = 9
Plug in 9 for x in one of the equation
-3(9) + 2y = -39
-27 + 2y = -39
2y = -12
Y = -6
In conclusion, x = 9, y = -6
The perimeter is 114 ft. because 680 divided by 17 is 40. 40+40+17+17= 114. I hope this helps! :)