Given that XY||BC
then,
In ΔABC
∠A+∠B+∠C=180o(property of triangle)
40o+30o+∠C=180o
70o+z=180o
z=180o−70o
z=110o
XY||BC
then
∠xo=∠B
∠xo=30o.
Now, In ΔAXY
∠xo+∠yo+∠A=180o(property of triangle)
30o+∠yo=40o=180o
∠yo=180o−70o
∠yo=110o
Hence, this is the answer.