Non-inverting amplifier gain?

I was given this circuit by a friend and I am trying to understand it. I have attached it to this post. I am trying to accurate calculate the gain of the circuit. My problem is the resistor 5VDC and R7 attached to the feedback resistor R3 and R2 on the inverting input of the op-amp. If it not for the 5VDC and R7, I could easily calculate the gain. My question is two fold:

1. What effect does the 5 volts and R7 have to the overall amplifier?
2. How would one calculate gain of this circuit?

Any insight on this would greatly be appreciated,
Tony

R7 and R2 are in parallel, since it is assumed that the impedance between the power rail and ground is zero.
Knowing that, the gain can be calculated from the standard formula for a non-inverting amplifier.
The resistors are arranged the way they are to ensure that the amplifier is biased above ground at DC,
cheers,
Richard

To solve the voltages for this circuit, figure out the voltage on the non-inverting input (it is a simple voltage divider). Once you know this (and assuming the opamp is ideal), assume the inverting input is at exactly the same voltage. Calculate the opamp output voltage required to generate that voltage at the inverting input (nodal analysis).

You now have the voltages for all nodes in the circuit. Calculating the gain depends on what you consider to be the input (gain = Vout / Vin).