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

Answer: Option B

Let A's speed = x km/hr
Then, B's speed = (7 - x) km/hr
So,
$$\begin{array}{rl}& \iff \frac{24}{x}+\frac{24}{\left(7-x\right)}=14\\ & \iff 24\left(7-x\right)+24x=14x\left(7-x\right)\\ & \iff 14x^2-98x+168=0\\ & \iff x^2-7x+12=0\\ & \iff \left(x-3\right)\left(x-4\right)=0\\ & \iff x=3\text{ or }x=4\end{array}$$
Since A is faster than B,
So, A's speed = 4 km/hr
And B's speed = 3 km/hr