How can you make the following equation true by drawing only one straight line: 5+5+5=550 ?

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?

Two in a corner, one in a room, zero in a house, but one in a shelter. What is it?

What is always in front of you but can’t be seen?

In a classic wine shop, the list of three most popular wines are:
- The cost of 1 French wine bottle: 500$
- The cost of 1 German wine bottle: 100$
- The cost of 20 Dutch wine bottles: 100$

John entered the wine shop and he needs to buy
- All three types of wine bottles.
- Needs to buy Dutch wine bottles in multiples of 20.
- Need to buy 100 wine bottles in total.

John has only 10000$. How many wine bottles of each type, John must buy?

There is a place where if I stand up straight, I will still be considered sideways.

What part of Turkey has the most feathers?

Can you count the number of lines in the below picture?

If,
29 - 1 = 30
9 - 1 = 10
14 - 1 = 15

Based on similar logic, Can you prove that the below algebraic equation is true?
11 - 1 = 10 ?

Is the statement valid that it does not matter how much older a sibling is, eventually the younger one will be half as old as the older one?