Car X began traveling at an average speed of 35 miles per hour. After 72 minutes, car Y began traveling at an average speed of 42 miles per hour. When both cars had traveled the same distance, both cars stopped. How many miles did car X travel from the time car Y began traveling until both cars stopped?	Choose the correct choice from the following answers
A) 105 B) 140 C) 175 D) 210 E) 245

Rationale: "in 72 minutes , car x travels 42 miles . car y gains 7 miles each hour , so it takes 6 hours to catch car x . in 6 hours , car x travels 210 miles . the answer is d ."
Answer: D