Christina has four daughters, and each of her daughters has a brother. How many children does Christina have?

John is selling fruits.
He sells grapes at $30, Dates $25, and a Wolfberry $45.
At what price does he sell fig?

PS: Logical Thinking

Speaking of rivers, a man calls his dog from the opposite side of the river. The dog crosses the river without getting wet, and without using a bridge or boat. How?

If you say my name, I will no longer exist. What am I?

I add 5 to 9 and get 2. The answer is correct, so what am I?

Find the missing number in the sequence below:

What Time Should the last watch show in the below figure?

If we change the South-East direction into North and North-East into West and all others similarly.
Can you find out which direction will be in the place of South-West direction?

Can you make a fire with just a single stick?

What is in seasons, seconds, centuries and minutes but not in decades, years or days?