The sum of a mother, her baby and her dog's weight is 170 Kg. How much does the baby weigh if the mother weighs 100 kg more than the combined weight of the baby and the dog, and the dog weighs 60 per cent less than the baby?

Take away the whole and some still remain. What is it?

I have a hole in my back and legs I lack.
I live where I can’t breathe and I eat without teeth.
What am I?

Can you start the fire using two pieces of wood?

I am sure no one can have two things for dinner. what are they?

How can one talk without saying a single word?

There are people and strange monkeys on this island, and you can not tell who is who (Edit: until you understand what they said - see below). They speak either only the truth or only lies.
Who are the following two guys?
A: B is a lying monkey. I am human.
B: A is telling the truth.

Spot what is wrong here in below Picture?

What goes up but never comes down?

What mathematical symbol can be put between 5 and 9, to get a number bigger than 5 and smaller than 9?