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

Which Number is the odd one out?

A) 7145
B) 2716
C) 5321
D) 4135

You have $100 with you and you have to buy 100 balls with it. 100 is the exact figure and you can't go below or above the numbers and you have to use the entire $100. If there is no kind of tax applied how many of each of the following balls will you be able to buy:

Green Balls costing $6
Yellow Balls costing $3
Black Balls costing $0.10

Now, how many of each must you buy to fulfil the condition given?

How can you spell "White of an egg" in one word?
Hint: I know you can spell coke, poke, and joke.

If 21x = 79x, what is the value of x?

There’s a one-story house in which everything is yellow. Yellow walls, yellow doors, yellow furniture. What colour are the stairs?

There are nine letters in the below-given diagram. You have to form a nine-letter word using these letters.

He runs but never walks. Murmurs, but never talks. Has a bed, but never sleeps. And has a mouth, but never eats?

Can you write down eight eights so that they add up to one thousand?

You are given four results as below:
1111 = F
2222 = E
3333 = T
Then, can you find out how to code 4444?