Suppose Azerbaijan is willing to trade 3 nails to Uzbekistan for every bolt that Uzbekistan makes and sends to Azerbaijan. Which of the following combinations of bolts and nails could Uzbekistan then consume, assuming Uzbekistan specializes in making bolts and Azerbaijan specializes in making nails? a. 12 bolts and 56 nails
b. 17 bolts and 40 nails
c. 7 bolts and 70 nails
d. 25 bolts and 15 nails

Because of the violent nature of the sport, professional american football players are at risk of suffering concussions (or brain injuries) during the violent collisions that occur between players during the game. violent collisions involving hits to the head are particularly risky. suppose the commissioner of the national football league (nfl) institutes a rule requiring players to wear a new, lighter helmet that is designed to reduce head trauma during collisions between players on the field. while the new helmets the probability of a concussion resulting from each individual collision, at the same time the new helmets could also give football players an incentive to play more , which could potentially the amount of violent collisions and thus the number of concussions suffered by nfl players, all else equal.