The speeds of three asteroids were compared. Asteroids X-13 and Y-14 were observed for identical durations, while asteroid Z-15 was observed for 2 seconds longer. During its period of observation, asteroid Y-14 traveled three times the distance X-13 traveled, and therefore Y-14 was found to be faster than X-13 by 4000 kilometers per second. Asteroid Z-15 had an identical speed as that of X-13, but because Z-15 was observed for a longer period, it traveled five times the distance X-13 traveled during X-13's inspection. Asteroid X-13 traveled how many kilometers during its observation?  Choose the correct choice from the following answers
A) 500	B) 1,600 / 3	C) 1,000	D) 1,500	E) 2,500

Rationale: "st + 2 s = 5 st t + 2 = 5 t 2 = 4 t t = 1 / 2 we are looking for distance ( d = s * t ) so we need to solve for speed now that we have time . speed y 14 - speed x 13 speed = d / t 3 d / t - d / t = 4000 ( remember , t is the same because both asteroids were observed for the same amount of time ) 2 d = 4000 2 = 2000 d = s * t d = 2000 * ( 1 / 2 ) d = 1000 answer : c"
Answer: C