(a) where the difference between the unbuilt area and the specified area exceeds five per cent. but does not exceed ten per cent. of aggregate area, by an amount equal to twenty per cent. of such value;

(b) where the difference between the unbuilt area and the specified area exceeds ten per cent. but does not exceed fifteen per cent. of the aggregate area, by an amount equal to thirty per cent. of such value;

(c) where the difference between the unbuilt area and the specified area exceeds fifteen per cent. but does not exceed twenty per cent. of the aggregate area, by an amount equal to forty per cent. of such value.

(a) "aggregate area ", in relation to the plot of land on which the property is constructed, means the aggregate of the area on which the property is constructed and the unbuilt area;

(b) "specified area ", in relation to the plot of land on which the property is constructed, means,

(c) "unbuilt area ", in relation to the aggregate area of the plot of land on which the property is constructed, means that part of such aggregate area on which no building has been erected.