if WX || YZ and m∠WSX = 180 and m∠YTZ = 180, then ∠WST and ∠STY are supplementary

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• ∠WST and ∠STY are supplementary, if (m∠ABC) + (m∠DEF) = 180, then ∠ABC and ∠DEF are supplementary
  • (m∠WST) + (m∠STY) = 180,

    if the following are true:

    • a + b = c
    • b = d

    then a + d = c

    • (m∠WST) + (m∠XST) = 180, if ∠ABC and ∠DEF are supplementary, then (m∠ABC) + (m∠FED) = 180
      • ∠WST and ∠TSX are supplementary, if m∠ABC = 180, then ∠ABX and ∠XBC are supplementary
        • m∠WSX = 180
    • m∠XST = m∠STY, if (WX || YZ) and (m∠WSX = 180) and (m∠YTZ = 180), then m∠XST = m∠STY
      • WX || YZ
      • m∠WSX = 180
      • m∠YTZ = 180