Boatman covers $x$ km against current in $t_1$ hr, with current in $t_2$ hr. Speed of boat = ?

Question

Accepted Answer

$\dfrac{x}{2}\left(\dfrac{1}{t_1} + \dfrac{1}{t_2}\right)$

Answer

$\dfrac{x}{2}\left(\dfrac{1}{t_2} - \dfrac{1}{t_1}\right)$

Answer

$\dfrac{x}{2}\left(\dfrac{1}{t_1} - \dfrac{1}{t_2}\right)$

Answer

$\dfrac{x(t_1+t_2)}{2}$

Boatman covers xxx km against current in t1t_1t1​ hr, with current in t2t_2t2​ hr. Speed of boat = ?