Respuesta :
Answer:
a = s/n - 1
Step-by-step explanation:
s = n(a + 1)
(switch the sides of the equation)
n(a + 1) = s
(now, divide both sides by n)
n(a + 1) = s
/n /n
-----------------
a + 1 = s/n
-1 -1 (subtract both sides by 1 now)
------------------
a = s/n - 1