or
or
The objective here is that 70% of the fruit in the box should be apples.
Now, there are 6 apples at start and there is no talk of removing any apples, so number of apples should remain 6 and they should constitute 70% of total fruit, so total fruit = 6/0.7 = 12 [approximate]
So we should have 12-6 = 6 oranges.
Right now, there are 27 oranges, so to get to 6 oranges, we should remove 27 - 6 = 21 oranges.
