At low altitudes the altitude of a parachutist and time in the air are linearly related. A jump at 2,500 feet lasts 100 seconds. (A) Find a linear model relating altitude a (in feet) and time in the air t (in seconds). (B) Find the rate of change of the parachutist in the air. (C) Find the speed of the parachutist at landing. (A) Find a linear model relating altitude a (in feet) and time in the air t (in seconds). a=mt+2500 (Type an equation using t as the variable.)