Replace the question mark with the correct number in the below-given picture?

A mother is 21 years older than her child. In exactly 6 years from now, the mother will be exactly 5 times as old as the child.
Where's the father?

I am something people love or hate. I change peoples appearances and thoughts. If a person takes care of them self I will go up even higher. To some people I will fool them. To others I am a mystery. Some people might want to try and hide me but I will show. No matter how hard people try I will Never go down. What am I?

A father's child, a mother's child, yet no one's son.

Who am I?

If you’ve got me, you want to share me; if you share me, you haven’t kept me. What am I?

I can turn polar bears white.
I can make anyone dance.
I can make everyone cry
I can make your hands clap
I can make you thin.
I can make you smile.
I can make you smile

Can you guess the riddle?

You want to boil a two-minute egg. If you only have a three-minute timer (hourglass), a four-minute timer and a five-minute timer, how can you boil the egg for only two minutes?

At the local model boat club, four friends were talking about their boats.

There were a total of eight boats, two in each colour, red, green, blue and yellow. Each friend owned two boats. No friend had two boats of the same colour.

Alan didn't have a yellow boat. Brian didn't have a red boat but did have a green one. One of the friends had a yellow boat and a blue boat and another friend had a green boat and a blue boat. Charles had a yellow boat. Darren had a blue boat, but didn't have a green one.

Can you work out which friend had which coloured boats?

Three doctors said that Bill was their brother. Bill says he has no brothers. How many brothers does Bill actually have?

What number comes next in the series?

5 15 5 18 5 24 14 20 _