Question

Given ________, – 243, – 226, – 209, – 192, – 175, …

a. What is the 67th term of the sequence
b. What is the series of the first 27 terms of the sequence

Answer 1

a = -243
d = -226 - (-243) = 17
term(67) = a + 66d
= -243 + 66(17) = 879

sum(n) = (n/2)(2a + (n-1)d)
sum (27) = (27/2)(-486 + 26(17))
= -594

Here is a nice new part to the question:
For which terms does the sequence switch from negative to positive ?

Answer 2

Just looked at the first of the "Related questions" below, which I had answered in June, and realized that your _____ , meant that -243 was actually the second term

I am pretty sure you can make the suitable adjustments.
(your first term will be -260)