In the metropolis of Bombay, the authority to levy property tax is vested with the Bombay Municipal Corporation. The basis for levy is the rateable value which is fixed under Section 154 of the Bombay Municipal Corporation Act (3 of 1888). Section 154(1) reads thus : "In order to fix the rateable value of any building or land assessable to a property tax, there shall be deducted from the amount of the annual rent for which such land or building might reasonably be expected to let from year to year a sum equal to ten percectum of the said annual rent and the said deduction shall be in lieu of all allowance for repairs or any other account whatsoever."  Prom the foregoing provision it is clear that the property tax is to be levied on the rateable value, which is to be fixed after deducting for repairs, etc., ten per cent from the amount of the annual cent. Annual rent of property is merely defined as that rent for which such property might reasonably be ....