eg1 and eg2

Eg. 1: A rectangular piece of land is to be fenced using two kinds of fencing. Two opposite sides will be fenced using standard fencing with a cost of $6/m, while the other 2 require heavy duty fencing that cost $9/m. What are the dimensions of the rectangular lot of greatest area that can be fenced for a cost of $9000. MCV4U Eg.2: A railroad between two cities carries 10 000 passengers per year when the fare is $50. If the fare goes up, the number of passengers will decrease, since more people will drive. It is estimated that each $10 increase in fare will result in 1000 fewer passengers per year. The train can not carry more than 13000 passengers per year. a) At what fare will the train have no passengers? b) What fare will maximize revenue? c) When revenue is maximized, how many people will ride the train each year