Answer:
D. Even-odd identity and simplifying further
Note first that several months have 30 days (each): April, June and September.
(A) could not be correct, since the month in question could have 28, 29 or 31 days.
(B) See (A), above. If the month in question does not have 30 days, then the month could NOT be April, June or September. Reject (B).
(C) You do this one, similarly to my responses to (A) and (B), above.
(D) This one is true, since we know that June has 30 days. If the month in question does NOT have 30 days, then that month could not possibly be June.
1ml of 80ml bottle: 55/80 = 0.6875 pence
1ml of 50ml bottle: 45/50 = 0.9 pence
If no special offer the first bottle is a better value for money.
Since special offer though, you'd be buying;
50ml bottle £45 + another 50ml £22.5 = £67.5 in
which case 1ml would cost;
67.5/100 = 0.675 pence. Hence buying 2x50ml
bottle would be a better value.
