Simulation of inverting summing amplifier not working and finding it's parameters
Here's the pin-out of a 741: -



Please note the following: -


Positive supply is to pin 7 not pin 5
Negative supply is to pin 4 not pin 1
Negative feedback is from output to the inverting input NOT the non-inverting input
The gain is inverting i.e. the minus sign is associated with the gain being inverted as in +1v becomes -1v therefore Rf is a positive value.