Find the mistake in the below maths equations

A = 2
A(A-1) = 2(A-1)
A2-A = 2A-2
A2-2A = A-2
A(A-2) = A-2
A = 1

If there are fifteen crows on a fence and the farmer shoots a third of them, how many crows are left?

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but there is only one right place for me.
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Can you find the key in the picture below?

What has many keys but can’t open a single lock?

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With the help clues provided in the image, can you find the 5 digit key?

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