Answer:
common ratio r = [tex]\frac{8}{5}[/tex]
Step-by-step explanation:
the nth term of a geometric sequence is
[tex]a_{n}[/tex] = a₁ [tex](r)^{n-1}[/tex]
a₁ is the first term, r the common ratio, n the term position
The expression inside ∑ is in this form
with a₁ = 7 and r = [tex]\frac{8}{5}[/tex]
