Answer:
The answer is 5, 10, 15, 20 or any positive multiples of 5
Explanation:
Since the ratio of green grapes to the total number of grapes is 9:14 and there are only purple and green grapes on the shelf. It implies the total number of purple grapes to overall grapes is 5:14.
Since this ratio is already at it's lowest form, it implies the possible number of purple grapes are 5, 10, 15, 20 or any positive multiple of 5.