Two airplanes leave dallas at the same time and fly in opposite directions. one airplane travels 80 miles per hour faster then the other. after 3 hours, they are 2490 miles apart. what is the speed of each airplane?

recall d = rt, distance = rate * time.

let's say airplane A is going at a rate of "r", therefore airplane B is moving faster, at a rate of "r + 80".

now, after 3 hours, both planes have been travelling for 3 hours each, and say if A has covered "d" miles, then B has covered the slack of 2490 - d.

f(x) has value 150 at x= 0

and 0 at x= 3

so d(f(x))/dt = slope = -150/3 = -50