Two dogsled teams raced across a 300-mile course in Wyoming. Team A finished the course in 3 fewer hours than did team B. If team A’s average speed was 5 miles per hour greater than that of team B, what was team B’s average speed, in miles per hour?  Choose the correct choice from the following options
A) 12
B) 15
C) 18
D) 20
E) 25

Rationale: speed of b = s speed of a = s + 5 time taken by b = 300 / s time taken by a = 300 / ( s + 5 ) difference in their time is 3 hrs . 300 / s - 3 = 300 / ( s + 5 ) plug in the values from the option no need of choosing 12 & 18 it wo n ' t satisfy a ) if we take 15 then t ( b ) = 300 / 15 = 20 t ( a ) = 300 / 20 = 15 . hence from this option difference comes out to be 5 which is not correct b ) if we take 20 then t ( b ) = 300 / 20 = 15 t ( a ) = 300 / 25 = 12 difference in timing is 3 hence option d is correct
Answer: D