Question: How do I check a group in Maple?

Hello, I am beginner with Maple 18, started recently, so I have some silly questions. I'm training the algebra study in Maple and got a list of exercises on the Internet, where they were asked to Prove it {5, 15, 25, 45, 55, 65} is a group with mod multiplication operation 90. If so, calculate the identity element and inverse of any element.

I tried to solve simply and easily using the type command (attached), but doesn't. Not appear any error, but results in false (and it's true). So I think you're missing something, but I can't see what. I would like to continue using this command, can anyone give me a hint on how to improve? Thank you!

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