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

Divide 110 into two parts so that one will be 150 per cent of the other. What are the 2 numbers?

Replace the question mark with the correct number, given the pair of numbers exhibits a similar relationship?

? : 3839 :: 11 : 1209

There is a square of a particular number which when doubled, becomes 7 more than its quarter.

Can you find the number?

John replied, when asked how old he was. In 2 years he will be twice as old as he was five years ago.' How old is he ?

You need to arrange three 7 and mathematical symbols to form number 1?

0 0 0 = 6
1 1 1 = 6
2 2 2 = 6
3 3 3 = 6
4 4 4 = 6
5 5 5 = 6
6 6 6 = 6
7 7 7 = 6
8 8 8 = 6
9 9 9 = 6

You can use any mathematical symbols in the space provided to make all above algebraic expressions true.

Which three-digit number, made of consecutive digits, like 567, is 2 less than a cube and 2 more than a square?

In a school, there are four subjects. Seventy percent of students study English, seventy five percent of students study Science, eighty five percent of students study Mathematics and eighty percent of students study Spanish.

Can you calculate the percentage of students that study all four subjects?

What will be the best approach to finding all the prime numbers less than 75 that leave an odd reminder when we divide them with 5?