Answer:
UW = UV + VW
substitute:
[tex]7x + 16 = (x + 13) + (15) \\ 7x + 16 = x + 28 \\ 7x - x = 28 - 16 \\ 6x = 12 \\{ \underline{ \: \: x = 2 \: \: }}[/tex]
then find UW:
[tex]UW = 7x + 16 \\ = 7(2) + 16 \\ = 14 + 16 \\ \\ { \boxed{ \boxed{ \: \: UW = 30 \: \: }}}[/tex]