Finding closed loop gain and Ip and In current in op amp

[whatphysics]

Homework Statement

Finding closed loop gain and Ip and In current in op amp

Homework Equations

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The Attempt at a Solution

I started by trying getting voltage divider for points between R1 and R2 as (R2/(R2+R1))Vs and between R4 and R5 similarly. And I'm not sure how to continue on. Any help would be greatly appreciated.

Thanks! Full questions uploaded

 

[gneill]

I started by trying getting voltage divider for points between R1 and R2 as (R2/(R2+R1))Vs and between R4 and R5 similarly. And I'm not sure how to continue on.

Assuming the simplifying properties of an ideal op-amp, what can you say about the current through R1? What then must be the potential at the junction of R1 and R2?