Answer:
(C). 6
Step-by-step explanation:
[tex]3\frac{9}{10}[/tex] + [tex]5\frac{1}{x}[/tex] = [tex]9\frac{1}{15}[/tex]
[tex]5\frac{1}{x}[/tex] = [tex]9\frac{1}{15}[/tex] - [tex]3\frac{9}{10}[/tex] = [tex]6\frac{2-27}{30}[/tex] = [tex]5\frac{32-27}{30}[/tex] = [tex]5\frac{5}{30}[/tex] = [tex]5\frac{1}{6}[/tex] ⇒ x = 6
