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

When you say goodbye, I am what you need to tie.
I come as a couple and go wherever you run.
Who am I?

A man who was outside in the rain without an umbrella or hat didn’t get a single hair on his head wet. Why?

A mother is 21 years older than her child. In exactly 6 years from now, the mother will be exactly 5 times as old as the child.
Where's the father?

What does this Rebus Picture mean?

Which Burger Is Different in below image?

1 + 9 + 8 = ?
considering, 28 + 8 + 92 = 10

Get total of 120 by using five zeros 0,0,0,0,0 and any one mathematical operator.
Do you ?

What has lots of eyes, but can’t see?

What is the next number in this matchsticks series riddle?