Find the 300th term

Question

Sn= 1/2n -25

Answer 1

If Sn is supposed to be the nth term, then
if you meant to say that Sn = 1/2 n - 25 (and not 1/(2n) - 25)
since d = 1/2 and S1 = -49/2,
S300 = -49/2 + 299(1/2) = ____