Respuesta :

Answer:

an = a(n-1) - 7

Step-by-step explanation:

the second term is smaller than the first term 7.

a20 = a19 - 7

a19 = a18 - 7

=> a20 = (a18 - 7) - 7

Then you can accumalate until a1

-> a20 = a1 - 19*7 = 86 - 19*7 = -47