Question 314406
Ok so first this is an arithmetic equation. To find the sum, you would use this formula:

S(n)=(n/2)(a1+a(n))
a1 being the first number in the sequence.

To find the 30th term, we use the definition of a arithmetic series:

a(n)= a1+(n-1)r    => a(30)=6+29(4)=122

Therefore:

s(30)=(30/2)(6+122)= 1920 

i hope this helps!