Answer:
y, because ∆RST~∆VUT.
Explanation:
As the two triangles share a vertex, the angles opposite by that vertex have the same measure, so STR~UTV. Then, both triangles also have another common angle with measure 55°, that is ∆RST~∆VUT . Then, the missing angle for both triangles will also have the same measure since
55+STR+y = 180 and 55+STR+TVU = 180
y = 180-55-STR and TVU = 180-55-STR
then, y~TVU.