 There are six assignments completed by the students lying on the table of the class teacher.
 These assignments are named as U, V, W, X, Y, and Z.
 V,W and Y are assignments on Economics while others are on Geography.
 Assignments X and Z are marked and others are not marked.
 Assignments U, W and X are written in English while others are written in Sinhala.

Which is the unmarked assignments on Economics written in English?