The length of the rectangular bookmark required to Ella is 16 minus thrice its width. If the perimeter is 20 inches, determine its length and width.

Answer 1

L = 16 - 3 w
L + w = 20/2 = 10
so L = 10-w
10 - w = 16 - 3 w
2 w = 6
w = 3
L = 10 - 3 = 7
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check
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16 - 9 = 7 sure enough
2(7) + 2(3) = 14 + 6 = 20 . Whew !

Answer 2

L = 16-3W
2(16-3W)+2W = 20
16-3W+W = 10
W = 3 in.
L = 16-3W = 16-9 = 7in.

9