Why is a river so rich ?

The answer I give is yes, but what I mean is no. What was the question?

Find the missing number in the sequence below:

Decode below rebus
D
N
A
T
S , D

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?

What country can make you shiver?

You walk into a room that contains a match, a kerosene lamp, a candle and a fireplace. What would you light first?

A bomb exploded in a room full of married couples and no one died. How?

People are waiting in line to board a 100-seat aeroplane. Steve is the first person in the line. He gets on the plane but suddenly can't remember what his seat number is, so he picks a seat at random. After that, each person who gets on the plane sits in their assigned seat if it's available, otherwise, they will choose an open seat at random to sit in. The flight is full and you are last in line. What is the probability that you get to sit in your assigned seat?

If,

6 / 7 = 2
3 / 9 = 7
8 / 2 = 6

Then

4 / 5 = ?