11.25 seems to be the answer they want, despite the lack of important information.
The answer appears to be 2 dollars for 3 pounds because the pattern seems like 2,4,6
If the original price was 'p', the new price would be 'p - 10%p' or 'p - 0.1p'. We know this is equal to 305, so 'p - 0.1 p = 305' would be the equation.
3 to the third power = 9
2 Open Bracket 64 - (3 x 7) close bracket = 86
9 + 86 = 95