The cost of building an airplane with 200 seats is about $100 million. If the cost, in millions of dollars, c, is proportional to the number of seats, s, what equation can be used to determine the cost, in millions of dollars, to build an airplane with any number of seats?

Amountain climber starts a climb at an elevation of 453 feet above sea level at his first rest stop he has climbed 162 feet and by his second rest stop he has climbed another 207 feet its getting late in the day so the climber starts his way down if the climber desends 285 feet how much does he need to ascend or descend to return to the original starting point