20
25
45
65
Correct answer is B
xo + zo = 180o (sum of < on str. line)
45o + zo = 180o
zo = 180o - 45o
z = 135o
z + yo + 20o = 180o (sum of < s in \(\bigtriangleup\))
135o + yo + 20o = 180o
yo + 155o = 180o
yo + 180o - 155o
yo = 25o