Answer
The mutual inductance is $~~1.67~mH$
Work Step by Step
We can find the mutual inductance:
$\mathscr{E}_1 = -M~\frac{di_{2}}{dt}$
$M = -\frac{\mathscr{E}_1}{\frac{di_{2}}{dt}}$
$M = -\frac{-25.0~mV}{15.0~A/s}$
$M = 1.67~mH$
The mutual inductance is $~~1.67~mH$
