Answer:
= 5

Explanation:
there is a common ratio between consecutive terms , that is
10 ÷ 5 = 20 ÷ 10 = 40 ÷ 20 = 80 ÷ 40 = 2
this indicates the sequence is geometric with explicit formula
= a₁

where a₁ is the first term and r the common ratio
here a₁ = 5 and r = 2 , then
= 5
