Answer:
3 cm
Explanation:
The given relation between length and width can be used in the perimeter formula to find the width.
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Let w represent the width of the rectangle in centimeters. The length is 4 cm more, so can be represented by (w+4). Using these values and the given perimeter in the perimeter formula, we find ...
P = 2(L +W) . . . . . perimeter formula
20 = 2((w +4) +w) . . . . known values substituted
10 = 2w +4 . . . . . . . . divide by 2, collect terms
6 = 2w . . . . . . . . . subtract 4
3 = w . . . . . . . . divide by 2
The width of the rectangle is 3 cm.
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Additional comment
The length is 7 cm.