How can you take 2 from 5 and leave 4?

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 ?

John and his wife were living in a rural place. On a particular day, John's wife fell ill and he called the local doctor. When the doctor picked up, he said, "Doctor, my wife is ill. She might have appendicitis."

"This can't be possible! I took out her appendix two years ago myself," the doctor explained.

When diagnosed, John's wife was found to have appendicitis. How can this be possible?

What has 88 keys?

In the below-given picture of a pretty girl, there is something wrong. Can you find out what it is?

Below is the sum of symbols in each row and column in the figure. Analyzing the figure, can you find out the value of the symbols?

The peacock is a bird that does not lay eggs. How do they get baby peacocks?

Which English verb becomes past tense just by rearranging the letters?

How many pluses should we put between the digits of 987654321 to get a total of 99, and where?

What is 3/7 chicken, 2/3 cat and 2/4 goat?