Total mass of fruits -> 9u
Mass of banana -> 2/9 × 9u = 2u
Mass of apples -> 9u – 2u = 7u
Since equal mass of apples and bananas were sold, the mass difference before and after were same.
7u – 2u = ½ kg
5u = ½ kg
1u = 1/10 kg
Mass of apples at first -> 7u = 7 × 1/10 = 7/10 kg