Mamun is faster than Jahid. Mamun and Jahid each walk 24 km. The sum of their speeds is 7 km/hr and the sum of time taken by them is 14 hours. Then Mamun's speed is equal to:

Let Mamun's speed = x km/hr
Then, Jahid's speed = (7 - x) km/hr
So,
(24/x) + {24/(7 - x)} = 14
⇒24(7 - x) + 24x =14x(7 - x)
⇒ 168 - 24x + 24x = 98x - 14x²
⇒ 14x² - 98x + 168 = 0
⇒ 14(x² - 7x + 12) = 0
x² - 7x + 12 = 0
x² - 3x - 4x + 12 = 0
x(x - 3) - 4(x - 3) = 0
(x - 3)(x - 4) = 0
x = 3, 4
Mamun is faster than Jahid
Mamun's speed = 4 km/hr.
Jahid's speed = 3 km/hr.