Question

how is it possible
someone tell me with step by step instructions

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Answer 1

$\huge{\underline{\underline{\sf{\red{[☆☆Answer☆☆]}}}}}$

$\frac{x}{2} + 90° - \frac{x}{2} \\ \\ = > \frac{x \: + 180° - x}{2} \\ (x \: and \: - x \: became \: 0)so \\ \\ = > \frac{180°}{2} = 90 °$