Answer: The percentage would be 19%, 51% and 30%.
Explanation:
Since we have given that
Number of food eaten by X = 57
Number of food eaten by Y = 153
Number of food eaten by Z = 90
Total number of food eaten = 
So, Food percentage of flock X = 
Food percentage of flock Y = 
Food percentage of flock Z = 
Hence, the percentage would be 19%, 51% and 30%.