If a, b, c are in AP or GP or HP, then $${{a - b} \over {b - c}}$$ is equal to

If the ratio of AM and GM of two positive numbers a and b is 5 : 3, then a : b is equal to

If $$x = 1 - y + {y^2} - {y^3}....$$ up to infinite terms, where $$\left| y \right| < 1$$, then which one of the following is correct?

What is the sum of all two-digit numbers, which when divided by 3 leave 2 as the remainder?