Problema Solution
City A and City B are 280 km apart. Harry rides his bike 10 km per hr faster than Yoshi rides his bike. Find​ Harry's average speed if he travels from City A to City B in 1 and two fifths hr less time than Yoshi.
Answer provided by our tutors
v = Yoshi's average speed
t = Y0shi's time
v + 10 = Harry's average speed
t - 1 2/5 = t - 7/5 Harry's time
d = 280 km the distance between the cities
Since distance = speed*time we have:
vt = d
vt = 280
t = 280/v
(v + 10)(t - 7/5) = d
(v + 10)(280/v - 7/5) = 280
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v = 40 km/hr
We need to ignore the negative solution since the speed can only be positive.
40 + 10 = 50
Harry's average speed is 50 km/hr.