\( \Large \left(v_{1}+v_{2}\right)t_{1} = \left(v_{1}-v_{2}\right)t_{2} \)

Therefore, \( \Large \left(v_{1}+2\right) \times 6 = \left(v_{1}-2\right) \times 9 \)

 \( \Large v_{1} = 10 km/hr \)