During a trip, Francine traveled x percent of the total distance at an average speed of 40 miles per hour and the rest of the distance at an average speed of 60 miles per hour. In terms of x, what was Francine’s average speed for the entire trip?
A.(180-X)/2
B.(X+60)/4
C.(300-X)/5
D.600/(115-X)
E.12000/(X+200)
Answer: E
這題是不是有少給條件?麻煩各位大大指教
