a. RB−→− + BF−→− + JQ−→− + FJ−→ + HR−→− + QH−→− RB + BF + JQ + QH + HR + FJ = RB + BF + FJ + JQ + QH + HR = 0
b. BQ−→− + QR−→− + FH−→− + RF−→− BQ + QR + RF + FH = BQ + QR - RF - FH = 0
a. RB−→− + BF−→− + JQ−→− + FJ−→ + HR−→− + QH−→−
RB + BF + JQ + QH + HR + FJ = RB + BF + FJ + JQ + QH + HR = 0
b. BQ−→− + QR−→− + FH−→− + RF−→−
BQ + QR + RF + FH = BQ + QR - RF - FH = 0