On the first day of her vacation, Louisa traveled 100 miles. On the second day, traveling at the same average speed, she traveled 175 miles. If the 100-mile trip took 3 hours less than the 175-mile trip, what was the average speed, in miles per hour? Choose the most appropriate option
A) 27 B) 28 C) 25 D) 30 E) 35

Rationale: "( time ) * ( rate ) = ( distance ) - - > ( rate ) = ( distance ) / ( time ) - - > given : ( rate ) = 100 / t = 175 / ( t + 3 ) - - > 4 / t = 7 / ( t + 3 ) - - > 4 t + 12 = 7 t - - - - > 3 t = 12 . t = 4 - - - - > ( rate ) = 100 / 4 = 25 answer : c"
Answer: C