Findout output voltage of an opamp when given input voltage and open loop gain
Answer reformulated: 

As already noted, your circuit simplifies to:


When you close the loop the open-loop gain is reduced to the ratio \$ \frac{\text R2}{\text R1}\$ so, since it's an inverting amplifier, the output voltage becomes:
\$\ \ \text {Vout} = \ \ - \frac {\text R2}{\text R1} \times \text{Vin} \$