We get the basic configuration for the non-inverting amplifier,
which has this output/ input relationship.
Now if we want to add the contribution from our reference voltage,
we would do the same thing as what we did just a minute ago.
We would look at Vref, and
we would remove all other sources, we'd short circuit the voltage sources.
So we'd have a short circuit across this Vs, and
we would open circuit the current sources which we don't have in this problem.
So, if we look at that configuration, where we have Vref, R1, Rf and a short
circuit to ground at the non-inverting input, that is exactly what the circuit
looked like when we did the example for the inverting op amp configuration.
And so the output that we received from Vref, the contribution
to the output voltage is Rf/R1 x Vref.
So that's what the output of this circuit would give us.
It would give us contribution from this Vs, and a contribution from Vref.