Answer:
28 sandwiches
Explanation:
If Jack takes 7 minutes to make a pie, the time that would take Jack to produce 4 pies is:
Jack would be willing to trade away the amount of sandwiches he is able to produce in 28 minutes to get 4 pies from Rodger. In 28 minutes, the number of sandwiches Jack can produce is:
Jack would be willing to trade away 28 sandwiches for 4 pies.