Fred and Sam are standing 55 miles apart and they start walking in a straight line toward each other at the same time. If Fred walks at a constant speed of 6 miles per hour and Sam walks at a constant speed of 5 miles per hour, how many miles has Sam walked when they meet? Choose the correct choice:
A) 5
B) 9
C) 25
D) 30
E) 45

Rationale: "relative distance = 55 miles relative speed = 6 + 5 = 11 miles per hour time taken = 55 / 11 = 5 hours distance travelled by sam = 5 * 5 = 25 miles = c"
Answer: C