HKIMO 2020 Grade 5 National Final (Heat) Set 01 Question 9

Find $\frac1{243}+\frac1{81}+\cdots+\frac19+\frac13+1+3+9+\cdots+81+243$. Write the answer as a mixed fraction.

Source glossary (English–Vietnamese): Value: giá trị; Mixed fraction: hỗn số.