Question on: JAMB Mathematics - 2006

∠PSQ = 90^o (∠ in semi circle)

∠PSQ + ∠QSR = 145^o

90 + ∠QSR = 145

∠QSR = 145 - 90

∠QSR = 55^o

BUt x^o = ∠QSR (∠s in the same segment)

∴x^o = 55^o