Use a coordinate plane to create a rectangular park that has one corner at (−412, 312) and a perimeter of 30 units. Label the coordinates of each corner of the park. Then plot points with mixed number coordinates inside the park to represent a swing set, a slide, and a bench. Plot the slide farthest from the x-axis and the bench closest to the x-axis. What are the coordinates of the points you plotted?

Ive seen this before! the answer is b

So the first thing we do is to multiply the top equation by 3. the reason i want to do this is i notice there will be a 6y on both equations and can possibly add/subtract them. so we get 6y = -3x + 27. adding that and the second equation we get 6x = 27-15 which is 12. divide by 6 and we get 2. ∴ x = 2. substituting 2 into the first equation we get 2y = -2 + 9 which is 7. divide by 2 and we get 7/2. ∴ y = 7/2, x = 2.