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

A shepherd had 18 sheep, out of which, all but ten died.

Can you tell us how many sheep was he left with?

Find the combined weight of the Cat, Dog and Rabbit in the given picture.

I am a prime number.
The double of myself is equal to the square of me.

which number am I?

Jenifer and Jesica are having a conversation.

Jenifer: I am definitely not over 30.
Jesica: I am 28 and you are surely 5 years older to me at least.
Jenifer: No, you are at least 29.

You are told that both of them are lying throughout in the conversation. Can you find their respective ages?

I throw two dice simultaneously.

What is the probability of getting a sum as 9 of the two numbers shown?

John has played 50 ODI's and his average is 50. How many runs should he score in his 51st ODI, so that his average score jumps to 51?

What is the next number in this matchsticks series riddle?

You are stuck on an island where you have nothing. You find four pieces of paper somewhere on the island. What will be your strategy to escape from the island safely?

PS: No other resource is available to you on the island, neither can you build anything.

What will you call your mother's brother's brother-in-law?