Rtotal = 1/(1/R1 + 1/R2 + 1/R3)
Rtotal = 1/(1/1200 + 1/680 + 1/330)
Rtotal = 1/(0,000833 + 0,001471 + 0,003030)
Rtotal = 1/0,005334
Rtotal = 187,48ohm