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

Decode this picture on T-Shirt and tell what it says ?

A boy and a girl are sitting on the porch.
"I'm a boy," says the child with black hair.
"I'm a girl," says the child with red hair.
If at least one of them is lying, who is which?

John left on a horse on Thursday , was gone for two days, and came back on Thursday after completing his work. How did that happen?

The first box has two white balls. The second box has two black balls. The third box has a white and a black ball.

Boxes are labeled but all labels are wrong!

You are allowed to open one box, pick one ball at random, see its colour and put it back into the box, without seeing the colour of the other ball.

How many such operations are necessary to correctly label the boxes?

We can be boring,Or interesting.
We can be long,Or short.
We can have pictures,Or just words.
Many love us,But many also hate us.
What are we?

I throw two dice simultaneously.

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

A sea diver is a real show-off. He showed everyone that he can hold his breath underwater for 15 minutes.

I went to the diver and told him that I can be underwater for double the time i.e 30 minutes.
He responded that he will give me 100$ if I would be able to do it. I won 100$.

What did I do?

What has lots of eyes, but can’t see?

The dirtier I get, the whiter I look. Who am I?