Respuesta :

Answer:

Step-by-step explanation:

a1 = 100

r = 1/5

an = 100 (1/5)^(n - 1)

Try it. We have the answer for a_3

a_3 = 100 * (1/5)^(3 - 1)

a_3 = 100 * (1/5)^2

a_3 = 100 * 1/25

a_3 = 4  which is just what the series says should be the answer.