If all Goats are Sheep and all Sheep are Deers, are all Deers Goats ?

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 ?

Can you make a fire with just a single stick?

No one wants to have it, but if one got it, he does not want to lose it. What is It?

How many bananas can you eat if your stomach is empty?

What number do you get when you multiply all of the numbers on a telephone's number pad?

Can you find a five letter word that is left with only two letters if one is removed?

A Monkey, a squirrel, and an Eagle are racing to the top of the mango tree. Assuming all these animals are in perfect shape, Which animal will reach to Banana first?

A bomb goes off.
Carnage.
One person, only a few feet away, survives! How can this be?

John walks into the daily grocery shop and steals a $100 bill from the shop. An hour later John returns to the shop and buys some daily products for $40. John pays the owner the $100 bill and therefore the owner returns him $60.

How much money did the owner lose?