AlgebraMediumRectangle from its perimeter and a difference
Algebra practice question
A rectangle has a perimeter of 40 centimetres, and its length is 4 centimetres greater than its width. What is the length of the rectangle, in centimetres?
Answer: 12
l + w = 20 (half the perimeter) and l − w = 4. Adding: 2l = 24, so l = 12 (and w = 8).
Common wrong answers
- If you answered 8
- 8 is the WIDTH; the question asks for the length.
- If you answered 16
- 16 uses l + w = 20 with w = 4, treating the 4 as the width itself rather than the difference.
- If you answered 24
- 24 is 2l, one step short.
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