(3) Where (i) a composite charge is payable in respect of residential accommodation, food, drink and other services, or any of them, and the case is not covered by the provisions of sub section (2); or (ii) it appears to the Income tax Officer that the charges for residential accommodation, food, drink or other services are so arranged that the room charges are understated and the other charges are over stated, the Income tax Officer shall, for the purposes of subsection (1), determine the room charges on such reasonable basis as he may deem fit." Section 5(1) provides: "5.(1) Subject to the provisions of this Act, there shall be 885 charged on every person carrying on the business of a hotel in relation to which this Act applies, for every assessment year com mencing on or after the 1st day of April, 198 1, a tax in respect of his chargeable receipts of the previous year at the rate of fifteen per cent of such receipts: Provided that Where such chargeable receipts include any charges received in foreign ex change, then, the tax payable by the assessee shall be reduced by an amount equal to five per cent of the charges (exclusive of the amounts payable by way of sales tax, enter tainment tax, tax on luxuries or tax under this Act) so received in foreign exchange.