On a long drive, a truck covered P percent of the total

On a long drive, a truck covered P percent of the total distance on local road, where it drove only 30 mph. The rest of the trip, it traveled at 50 mph. In terms of P, which of the following represents the average velocity of the entire trip?

(A) P-10
(B) 50 - p/5
(C) (2P+1000)/40
(D) 10000/(p+200)
(E) 15000/(2P+300)

Would be grateful for any quick approach