Step-by-step explanation:
[tex]name \: each \: of \: the \: angle \: as \: in \: \\ the \: image \: i \: sent \\ like\: this \: \\ a + c \: = 180(opposite \: angle \: of \:a \: \\ cyclic \: quadrilateral) \\ same \: as \: b + d = 180 \\ x + 50 + a = 180 \: (angle \: on \: a \: \\ straight \: line ) \\ a = 180 - x - 50 \\ same \: as \: c \\ c = 180 - 2x - 40 \\ a + c = 180 \\ 180 - x - 50 + 180 - 2x - 40 \\ = 180 \\ collect \: like \: terms \: \\ - x - 2x = 180 - 180 - 180 + 40 \\ + 50 \\ - 3x = - 90 \\ x = 30[/tex]
