Question 242827
The question asks you to find the length and width of a rectangle that is 3 times as wide as it is tall.
Since it is a rectangle and parallel to the coordinate axis, we are confident in defining:
w = width
h = height = 3w
We will not use 'h' in the solution proper, but instead we will use w and 3w to keep to one unknown.
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We are told that the perimeter = 56.
We know the perimeter = 2w + 2h for all rectangles.
Substituting 3w for h, we have
56 = 2w + 2(3w) 
56 = 2w + 6w
56 = 8w
7 = w
w = 7
Substituting for w, we have
h = 3w = 3(7) = 21
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Now we know that point D is at (9,2), which is one corner.
Assuming it is the lower right corner, the coordinates can be calculated.
A = (9-w, 2) = (2,2)
B = (9-w, 2+h)= (2,23)
C = (9, 2+h) = (9, 23)