Two design options of a business building on a 10.0 hectare site are being compared for built-up area

Q. Two design options of a business building on a 10.0 hectare site are being compared for built-up area. Floor to floor height of Option A is 3.6 m and that of Option B is 4.5 m. If the maximum allowable building height is 45 m with same ground coverage for both options, the additional built  up area achievable in Option A over Option B is_______percent.

Ans: 20 to 20