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

In a town, there are four houses located at different distances from each other. Following are the distances:

The third house is 60 meters apart from the first house.
The fourth house is 40 meters apart from the second house.
The third house is 10 meters nearer to the fourth house than it is to the second house.

Can you find out the distance between the fourth and the first house?

There are 20 people in an empty, square room. Each person has full sight of the entire room and everyone in it without turning his head or body, or moving in any way (other than the eyes). Where can you place an apple so that all but one person can see it?

How will you measure 15 minutes using two hourglasses of 7 minutes and 11 minutes respectively?

The day after tomorrow will be three days before Tuesday. Can you find out what is today?

What word is represented by this rebus?

I am sure no one can have two things for dinner. what are they?

Why do you find that most of the buildings are deprived of the 13th floor?

A maths symbol is hidden in the below Bar Graph. Can you decipher it?

Decode below three cipher riddles:

26 L of the A
7 D of the W
1000 Y in a M