In the right triangle shown M

I'd be glad to answer the question, however you didn't include a picture of the triangle in your question or explain how it is in the post. If you edit the question or create a new one once again, i'd be glad to help.

cross multiplying, we get :

⇒ (3) × (5) = (9) × (x)

⇒ 15 = 9x

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