1) a farm has chickens and cows. you ask the farmer how many chickens he has, and how many cows he has. the farmer tells you he has 28 healthy animals, and they have a total of 64 legs. how many of his animals are cows?
2) andrew has a collection of soda bottles. some of them are 12-ounce bottles, and others are 16-ounce bottles. if the collection contains 20 bottles which hold a combined 300 ounces, how many of the soda bottles are 12-ounce bottles?
need two variables and two equations for each. it also needs to be solved.

Exercise: counting committees 0.0/2.0 puntos (calificable) we start with a pool of n people. a chaired committee consists of k≥1 members, out of whom one member is designated as the chairperson. the expression k(nk) can be interpreted as the number of possible chaired committees with k members. this is because we have (nk) choices for the k members, and once the members are chosen, there are then k choices for the chairperson. thus, c=∑k=1nk(nk) is the total number of possible chaired committees of any size. find the value of c (as a function of n ) by thinking about a different way of forming a chaired committee: first choose the chairperson, then choose the other members of the committee. the answer is of the form c=(α+nβ)2γn+δ. what are the values of α , β , γ , and δ ?