Respuesta :

Answer:

aₙ = -15 + 10 * (n-1)

Step-by-step explanation:

aₙ = a₁ + (n-1)*d       a₁: first term     d: common difference

a₅  a₁ + 4d =25 .... (1)

a₁₁  a₁ + 10d = 85   ...(2)

(2) - (1)     6d = 60

d = 10

a₁ = -15

Formula: aₙ = -15 + 10 * (n-1)