Respuesta :

Answer:

a. T² - T¹ = d ( A. P) -5

b. T²/T¹ = r (G. P) 3/4

Step-by-step explanation:

a. 15 - 20 = -5

b. 15/20 = 3/4

Answer:

This is an arithmetic sequence and the common difference is equal to -5.