sq bisects angle RST, and m ankle RSQ = 2x-4. write an expression for candle RST

if SQ bisects ∡RST, that means SQ is cutting it into two equal halves, namely ∡TSQ = ∡RSQ, and since we know that ∡RSQ = 2x - 4, then ∡TSQ = 2x - 4, thus
∡RST = ∡TSQ + ∡RSQ
∡RST = (2x - 4) + (2x - 4)
∡RST = 4x - 8.