Answer
$504$
Work Step by Step
Formula to calculate the sum of an arithmetic sequence is: $S_n=\dfrac{n}{2}(a_1+a_n)$ ...(1)
Here, $a_1: $ First term and $a_n=$last term
and $a_1: $ First odd term is 31 and $a_n$:last term is 53, thus the total odd terms are $12$.Then use equation (1) to get the sum of the sequence.
Thus, $S_{12}=\dfrac{12}{2}(31+53)\\=6(84)\\=504$
