Question

@florisalreadytaken

Answer 1

an arithmetic sequence -- its progressive right?

there is a formula for this (always if we know the value of \(l\))
\[ S_n=\frac{n}{2}(a+l) \]

Answer 2

where n is number of terms, a first term, l last term?

Answer 3

yes

Answer 4

29(6+405) = 29(411) = 11919

thank you xd