Answer:
1220
Explanation:
This can easily be done as follows,
Take the first term of the series, (a = -10)
Take the last term of the series, (l = 50)
The numbers of terms is n = 50+10+1 = 61
Now,
For sum,
S= n/2 (a+l) =60/2 (50+-10) = 61/2 (50-10) = 61/2*40 = 1220