Help me, please: A chairlift descends from a mountain top height of 5,600 ft. at a rate of 700 ft. per minute to pick up skiers at the bottom. The height in feet of the chairlift is a linear function of the time in minutes since it begins descending. Find the height (y) of the chairlift 3 minutes (x) after it begins descending.

a) Write a linear equation in slope-intercept form that describes the problem.