The average emf induced in the secondary coil is 0.10 V when the current in the primary coil changes from 3.2 to 2.0 A in 0.10 s. What is the mutual inductance of the coils?

V1 = M12 * DI2/dt

V1 is the EMF in circuit 1
I2 is the current in circuit 2 and dI2/dt is the rate of change, 20 A/s.
M12 is the mutual inductance.

Solve for M12