Answer: (a) The equation is so called "time equation"
D/12 + 16*60 + D/8 = 19*60 seconds
(b) To determine the distance D, solve the equation
D/12 + D/8 = 19*60 - 16*60 = 3*60
multiply both sides by 24
2D + 3D = 3*60*24
5D =4320
D =4320/5 = 864 ft
Explanation: