4.) Recursive formula => f(n + 1) = f(n) - 3
Explicit rule => f(n) = a + (n - 1)d = 35 + (n - 1)(-3) = 35 - 3n + 3 = 38 - 3n.
f(n) = 38 - 3n
5.) Recursive formula => f(n + 1) = f(n) + 7
Explicit rule => f(n) = 58 + (n - 1)7 = 58 + 7n - 7 = 51 + 7n
f(n) = 51 + 7n
