Find the mistake in the below maths equations

A = 2
A(A-1) = 2(A-1)
A2-A = 2A-2
A2-2A = A-2
A(A-2) = A-2
A = 1

Can you make four (4) nines (9) equal 100?

Cristina was born in 1888. She just had her 30th birthday today how did that happen?

Which tank will fill first?

A large container is kept in open under the rain. Every passing hour, the water collected inside the container becomes double what it was.

In ten hours, the container is filled completely. Can you calculate how long would it have taken to be filled in half?

Using eight eights and addition only, can you make 1000?

There are three light switches outside a room. One of the switches is connected to a light bulb inside the room.
Each of the three switches can be either 'ON' or 'OFF'.

You are allowed to set each switch the way you want it and then enter the room(note: you can enter the room only once)

Your task is to then determine which switch controls the bulb?

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

Replace the question mark with the correct number.

what one word does the below rebus identifies?