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 70 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 choices.
A) 15 B) 20 C) 40 D) 42 E) 68

Rationale: "car y began travelling after 72 minutes or 1.2 hours . let t be the time for which car y travelled before it stopped . both cars stop when they have travelled the same distance . so , 35 ( t + 1.2 ) = 70 t t = 1.2 distance traveled by car x from the time car y began traveling until both cars stopped is 35 x 1.2 = 42 miles answer : - d"
Answer: D