I'm pretty sure its A) 50 like what you said Alyssa.
I was not sure it was correct only
Donald eats 6 per minute so if you multiply it by 50 it will be 300. 500 - 300 = 200 burgers.
Wendy eats 4 per minute so if you multiply it by 50 it is 200. So 400 - 200 is 200 burgers.