(a) Assuming the individual is rational, they would only accept the job from Erebor if the wage was greater than their opportunity cost which is the wage that they could earn working 45 hours a week at Isengard. Hence the minimum wage to accept is Wi.

(b)  The minimum I’m willing to accept to work at Erebor does not change if I am indifferent between working online and working onsite. I would rather work for fewer hours for more wage than work more hours for fewer wages.

However, if my preference changes and I prefer working online, I would be willing to accept a lower wage assuming online working gives me higher utility and make up for the lower salary.

Similarly, if my preference changes and I prefer working onsite, the minimum to accept will be higher because working online gives me disutility and I require compensation for it.