Which of these is NOT a whole number?

Find the fraction of 0.538888...

Let A and B be two sets such that n(A – B) = 20 + x, n(B – A) = 3x and n(A∩B) = x + 1. If n(A) = n(B), then the value of (2x – 5) is:

Let p be the greatest number of 4-digits which when divided by 21, 22, 24 and 28, the remainder in each case is 8. What is the sum of the digits of p?

If the HCF of the expressions (x + 3) (2x² – 3x + a) and (x – 2) (3x² + 10x – b) is x² + x – 6, then what is the value of (2a – 3b) ?