Answer:
Which shop will benefit the most from its expansion?
The law of marginal returns applies here, that is why Sunshine donuts didn't produce twice as many by using more machines
How much should Donny realistically expect his production to increase with the new equipment?
Similar to the additional production that Sunshine had in the past.
How much should Sunshine realistically expect her production to increase with the new equipment?
Maybe even a little more than 50 dozen, but definitely less than 80 or 100.