Explanation:
this is one-dimensional ? everything just on one number line ?
TU = 2 - -17 = 2 + 17 = 19
TU is 19 units long (17 units on the negative side, and 2 units on the positive side of the number line).
therefore, to make TU = UV a true statement, UV has also to be 19 units long.
as U = 2,
V = U + UV = 2 + 19 = 21