book Maths Puzzle Numerical Ability

How do I first simplify then solve:
-1/9u^-5*(45u^-4)

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book Other Question

What is the distance between (2,-3) and (1,2) Radical expressions
Three students were asked to simplify sqrt10 +sqrt50. Their answers were:
Sqrt10(1+sqrt5),
Sqrt10+5sqrt2, and
Sqrt2(5+sqrt5).
Which if any is correct?
Which is in simplest form?
Thanks so much