Lewis will get zero sweets.
Step-by-step explanation:
There are a total of 69 sweets and these are divided by Rosie and Chloe only. Rosie has 20 and Chloe gets the rest which is 49.
20 from Rosie and 49 from Chloe = 20 + 49 = 69. Therefore, a total of 69 sweets. Nothing is left for Lewis.