Hi, I would like an explanation to this question please. I already have an answer to it but I don't understand how it is derived.

1. Let w be the number of whips and j the number of leather jackets. If Kinko's utility function is U(x, y) = min{7w, 4w + 12j}, then if the price of whips is $20 and the price of leather jackets is $40, Kinko will demand: (Answer: 4 times as many whips as leather jackets)
2. In Problem 1, if Abishag owned 10 quinces and 10 kumquats and if the price of kumquats is 2 times the price of quinces, how many kumquats could she afford if she spent all of her money on kumquats? (Do not have the laser for this one, could you please provide an explanation)
3. In Problem 1, the production function is given by F(L) = 6L2/3. Suppose that the cost per unit of labor is $12 and the price of output is 9, how many units of labor will the firm hire? (Do not have the laser for this one, could you please provide an explanation)
4. If output is produced according to Q = 4LK, the price of K is $10, and the price of Lis $5, then the cost minimizing combination of K and L capable of producing 2 units of output is (Do not have the laser for this one, could you please provide an explanation)

Thank you in advance.