in the InvertingAmplifier constructor I tried to call the super constructor with Amplifier(r1, r2) but it didn't work. I see that super(r1, r2) is the accepted way but I don't understand why.
public Amplifier( int resistance1, int resistance2)
{
r1 = resistance1;
r2 = resistance2;
}
public class InvertingAmplifier extends Amplifier
{
public InvertingAmplifier (int r1, int r2)
{
super(r1, r2);
}