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Good.

That works (only) with R6=R7=R8  so for N=3 resistors and then use voltage gain = Av+= N = 1+(R5/R9) = 3

If you wanted more flexibility to choose gains separately without having to change gain for the number of sources. then you would use the inverting inputs only and then Vin+ is a fixed reference.   Vref = Vin+ = V+/2 or whatever.  Sometimes Op Amps do not work on single supplies near 0V unless specified by Vcm specs.