He doesn't say the "The last time Robin asked me..." he says "The last Robin asked me..." indicating he meant the person who was Robin before the current one.
To be a little nitpicky, in #6, the nuggets labelled 4 and 5 are the same nugget cut in half. It was probably done to try to prove it is real chicken in the nugget.
The assumption of the question would not be the bounty hunters are paid 200 + 50 per spy a day but the Bounty Hunters receive 200 credits up front then 50 credits a spy. Since they each get 50 credits per spy captured, with 5 bounty hunters, that would be 50 * 5=250 a spy. With 2 spies a day that makes 500 credits a day. So, assuming no spies are sent the first day the bounty hunters are hired then the equation should be 200 + 500(t-1)= 700 + 100(t-1). Or if there are bounty hunters are sent the first day than 700+500(t-1)=700+100(t-1). I would assume the first equation would be what the student is looking for based on the last part of the question.