CBSE Class 10 Answered

In 2 hrs, A travels 24 km, hence his speed is 24/2 = 12 km/hr.

And if the speed of B is VB, then

2V_B + 24 = PQ

B travels for some time T, a distance of 24 km to reach P.

T = 24/VB,

and in the same time T, A travels 2VB but 20 km short.

T = (2V_B - 20)/V_A = (2V_B - 20)/12

Since the time is same,

24/V_B = (2V_B - 20)/12

2V_B² - 20V_B - 288 = 0

V_B² - 10V_B - 144 = 0

V_B² - 18V_B + 8V_B - 144 = 0

(V_B + 8)(V_B - 18) = 0

V_B = 18 km/hr

PQ = 24 + 18x2 = 60 km.

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Team,

TopperLearning.