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

How many times in a given day, minutes and hour clock comes in a straight line ?

You see me once in June, twice in November, and not at all in May. What am I?

How many times can you subtract the number two from the number fifty?

If a boy blows 18 bubbles,
Then pops 6 eats 7 and then
He pops 5 and blows 1.
How many are left?

1 rabbit saw 9 elephants while going to the river. Every elephant saw 3 monkeys going toward the river. Each monkey had 1 parrot in each hand. How many animals are going towards the river?

If six children and two dogs were under an umbrella, how come none of them got wet?

My grandson is about as many days as my son in weeks, and my grandson is as many months as I am in years. My grandson, my son and I together are 120 years. Can you tell me my age in years ?

What can you serve, but never eat?

Find The Next Number In The Sequence

30 10 15 13 0 16 -15 ?