Use only one mathematical symbol and all numbers (0-9) to get a sum of 99

Find out the missing number in the picture attached:

If I remove one from eleven it becomes Ten and if I remove one from nine also becomes Ten. How?

On rolling two dices (six-sided normal dice) together, what is the probability that the first one comes up with a 2 and the second one comes up with a 5?

There are 2 people near the river and both of them want to get on the other side. The boat can only take one of them. But they got across.
How?

2, 3, 5, 9, 17, _ What is the next number in the sequence?

You can win me and lose me but never buy me
You can not eat me and never want to part with me
I can make you cry or bring you joy
I am not a machine and definitely not a toy
You keep me but i am not forever just yours
You might find me in a case or on a shelf next to a vase
I am hard and i am tall if you bump me i am sure to fall
I am made of different materials and am at many events
If your lucky and fight hard I might be yours
What am I ?

I have Rs.50 and I spend it in the way as below.

I always drive my customer away.

Who am I?

Who always enjoys poor health?