Find the value of $$a_{2}+a_{4}+a_{6}+ \cdots+a_{98}$$ if $$a_{1},a_{2},a_{3},\cdots$$ is an arithmetic progression with common difference 1, and $$a_{1}+a_{2}+a_{3}+ \cdots+a_{98} = 137$$.

(第二届AIME1984 第一题)