the first problem :

it is all about summing voltages in the loop of i2 but WHY subtracting the induced voltage ?? (Note that the Dots are in the same direction)

and the second problem made it more confusing :

again summing voltages in loops , here we have the inductor L1 common in both loops , WHY on earth did he sum the induced voltage of L1 in the first loop and subtract the same induced voltage of the same inductor in the second loop (Note again the Dots are in the sam direction like the first problem)

Can someone help me understaind how these Dots determine when to sum / subtract the induced voltage ?? Thanks for your time.