Which alphabet letter is a question?

If,

A + B = C
D - C = A
E - B = C

Based on the above equations, find out the answer for:

D + F = ?

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

Count the number of lines in the image below ?

In a mathematical quiz, you are asked the following question:

Use three 9s in a mathematical expression without dividing or multiplying to form the number one.

Can you answer the question?

There are two beautiful yet remote islands in the South Pacific. The Islanders born on one island always tell the truth, and the Islanders from the other island always lie.
You are on one of the islands and meet three Islanders. You ask the first which island they are from in the most appropriate Polynesian tongue, and he indicates that the other two Islanders are from the same island. You ask the second Islander the same question, and he also indicates that the other two Islanders are from the same island.
Can you guess what the third Islander will answer to the same question?

I live in a bowl. I can swim. I have a tail. I also have fins and big eyes. What am I?

Can you count the number of squares in the figure below?

During which month do people sleep the least?

What am I?