On the first day of her vacation, Louisa traveled 240 miles. On the second day, traveling at the same average speed, she traveled 420 miles. If the 240-mile trip took 3 hours less than the 420-mile trip, what was the average speed, in miles per hour? Choose the correct choice from the following.
A) 65
B) 50
C) 55
D) 60
E) 58

Rationale: "( time ) * ( rate ) = ( distance ) - - > ( rate ) = ( distance ) / ( time ) - - > given : ( rate ) = 240 / t = 420 / ( t + 3 ) - - > 4 / t = 7 / ( t + 3 ) - - > 4 t + 12 = 7 t - - - - > 3 t = 12 . t = 4 - - - - > ( rate ) = 240 / 4 = 60 answer : d"
Answer: D