Given, (−5) + (−8) + (−11) + ………… + (−230)

For this A.P.,

First term, a = −5

nth term, a_n= −230

Common difference, d = a₂−a₁ = (−8)−(−5)

⇒d = − 8+5 = −3

Let −230 be the n^th term of this A.P., and by the n^th term formula we know,

a_n= a+(n−1)d

−230 = − 5+(n−1)(−3)

−225 = (n−1)(−3)

(n−1) = 75

n = 76

And, Sum of n term,

S_n = n/2 (a + l)

= 76/2 [(-5) + (-230)]

= 38(-235)

= -8930