How long did it take Helen to drive from her house to her mother's house?
1. Her average speed was 72 mph.
2. If her average speed had been 8 miles per hour greater, it would have taken her 1 hour less.
The multiple choice answers are (it's a GMAT problem):
A. Statement 1 is enough, but not statement 2.
B. Statement 2 is enough, but not statement 1.
C. Both Statement 1 and 2 are needed to answer this question.
D. Either statement can be used to answer this question.
E. Neither statement can be used to answer this question.
I chose E, but this exam says that the answer is C. I just don't see how this can be solved without a total distance and a time.
Thanks in advance.