Riddles of Why are lizards always happy?

Three sisters and two brothers.
This can be solved by simple deduction, but if algebra is used let x be the number of sisters and
y the number of brothers:
x+ 1= 2y
y+ 1= x
Therefore, y + 1+ 1= 2y
so y =2
or x + 1= 2x - 2
so x = 3

There is a boat and not one single person is on board? How is that possible?

Answer

They're all married!

I am a three digit number. My second digit is four times more than my third digit. My first digit is seven less than my second digit.
What Am I?

Answer

182

Replace the same characters by the same numerals so that the mathematical operations are correct.

SEND
+
MORE
---------

MONEY

Answer

9567 + 1085 = 10652

How many peas are there in a pint?

Answer

There is just one P in a 'pint'.

I never was, am always to be,
No one ever saw me, nor ever will
And yet I am the confidence of all
To live and breathe on this terrestrial ball.

Answer

Tomorrow