Operational Amplifier as Voltage summation or adder and subtractor.
operational amplifier - Op-amps in series – why does this op-amp subtractor not subtract? - Electrical Engineering Stack Exchange
Op-Amp as Difference Amplifier or Op-Amp as subtractor / Differential amplifier - YouTube
Glossary of Electronic and Engineering Terms 'Op Amp Adder', Summer Circuit
LM358-N: Help designing cascading amplifiers: voltage subtractor outputting to a non-inverting amplifier - Amplifiers forum - Amplifiers - TI E2E support forums
ADTRON Metal Op Amp As Adder & Subtractor Trainer, For Laboratory at Rs 6500 in Mumbai
Op-Amp Differential Amplifier Circuit | Spiceman
Arithmetic Circuits
OP-Amp as Differential Amplifier (Subtractor), Explained with Examples. - YouTube
Differential Amplifier or Voltage Subtractor Circuit
Analyze a Unique Inverting Op Amp: An Op Amp Subtractor - dummies