150 because 6 times 5 is 30 then you multiply whats inside the square root thing so you'd get 25, 25 is a perfect square which simplifies to 5 then 5 times 30 is 150.
(x + 1) x (x - 4). When you check it you will get your original expression.
First find the numbers that are divisible by 3.
3, 6, 9, 12, 15, 18, 21, 24
There are 8 numbers divisible by 3 so there are 16 that are not divisible by 3.
P(not div by 3) = 16/24 = 2/3