1.Mum is five times as old as my sister.In 15 years mum will

1.Mum is five times as old as my sister.In 15 years mum will be twice as old as my sister.How old is mum now?
2.Tom stands in a room.There is nothing but two dongs and five little dogs in it.How many legs are there in the room?
3.I am a number.I am inside the circle.I am number that is less than five.I am not in the rectangle.What number am