Strategies and Hints
The correct answer is 80. The quick fallacy here is to assume the banner
is 40 + (40)
or 60. However if this were true,
the length of the banner would be (60)
or 30, and the total length of the banner should be 70. You arrive at
the correct solution by letting x = length of the banner and solving
the equation x = 40 +
x.
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