Answer:
[tex]\boxed{\frac{1}{10}}[/tex]
Step-by-step explanation:
[tex]\frac{9}{10}+(-\frac{4}{5})\\\\ \frac{9}{10}-\frac{4}{5}\\\\\text{LCM} (10,5): 10\\\\\rightarrow \frac{4*2}{5*2}=\frac{8}{10}\\\\\frac{9}{10} -\frac{8}{10}\\\\\boxed{\frac{1}{10}}[/tex]
Hope this helps.
