Two coils 'P' and 'Q' are separated by some distance, When a current of 3A flows through coil 'P', a magnetic flux of $10^{-3} Wb$ passes through 'Q'. No current is passed through 'Q'. When no current passes through 'P' and a current of 2A passes through 'Q', the flux through 'P' is:

$6.67×10^{-4} Wb$

$\text{Flux passes through a coil can be given as }\phi = MI$ 

$\Rightarrow M = \frac{\phi}{I} = \frac{10^{-3}}{3}$

$\text{When 2A passes through Q then Flux through P is } \phi'= MI' = \frac{10^{-3}}{3}\times 2 = 6.67\times 10^{-4} Wb$