book Maths Puzzle Numerical Ability

Probability problem:

There are 5 red and 4 black balls in a box. If you pick out 3 balls without replacement, what is the probability of getiing at least one red ball?

I have tried so far: P(5/9) + P(4/9) - (3/9)= (6/9)≈ 2/3

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book Other Question
Take any number. Add 10, multiply by 2, add 100, divide by 2 and subtract the original number. The answer will be the number of minutes in a hour. Why? 2) For the function y = x2 - 4x - 5, perform the following tasks:
a) Put the function in the form y = a(x - h)2 + k.

b) What is the line of symmetry?



college algebra