(a)  any income from investment or income from long-term capital gains of an asset other than a specified asset;

(b)  income by way of long-term capital gains,

the tax payable by him shall be the aggregate of—

 (i)  the amount of income-tax calculated on the income in respect of investment income referred to in clause (a), if any, included in the total income, at the rate of twenty per cent;

(ii)  the amount of income-tax calculated on the income by way of long-term capital gains referred to in clause (b), if any, included in the total income, at the rate of ten per cent; and

(iii)  the amount of income-tax with which he would have been chargeable had his total income been reduced by the amount of income referred to in clauses (a) and (b).