Answer:
a₂₀ = 69
Step-by-step explanation:
The nth term of an arithmetic sequence is
[tex]a_{n}[/tex] = a₁ + (n - 1)d
where a₁ is the first term and d the common difference
Here a₁ = 12 and d = 15 - 12 = 3 , then
a₂₀ = 12 + (3 × 19) = 12 + 57 = 69
