Shortly after takeoff, a plane increases altitude at a constant rate. The plane's altitude is 10000 feet in 5 minutes. The plane reaches an altitude of 21000 feet in 10 minutes. a. If the altitude depends on the time, find the slope of the line. slope = {feet} b. Write linear function, in the form of y=mx+b, that expresses the altitude of the plane as a function of time. c. What is the altitude of the plane in 8 minutes? d. How long will it take for the plane to reach its cruising altitude of 32,000 feet?