Part a) is partially correct. You need to change that 35 to 36.
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Part b)
W = width
L = length = W+5
P = perimeter of rectangle
P = 2L+2W
25 < P < 36 ... from part a)
25 < 2L+2W < 36
25 < 2(W+5)+2W < 36
25 < 2W+10+2W < 36
25 < 4W+10 < 36
25-10 < 4W+10-10 < 36-10 ... subtract 10 from all sides
15 < 4W < 26
15/4 < 4W/4 < 26/4 ... divide all sides by 4
3.75 < W < 6.50
The graph is shown in the diagram below.
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Part c)
L = W+5
W = L-5
3.75 < W < 6.50 ..... result from part b)
3.75 < L-5 < 6.50
3.75+5 < L-5+5 < 6.50+5 ... add 5 to all sides
8.75 < L < 11.50
The graph is shown in the diagram below.
