Answer:
[tex]\Large \boxed{\sf 7 \times 3 ^{3-n}}[/tex]
Explanation:
This is a geometric sequence
Use nth term of geometric sequence formula
[tex]a_1 \times r^{n-1}[/tex]
Ratio is 27/63=1/3
First term is 63
[tex]\displaystyle 63 \times (\frac{1}{3}) ^{n-1}[/tex]
Simplify expression
[tex]\displaystyle 7 \times 3 ^{3-n}[/tex]
