Answer :
Let G be the number of green marbles and B the number of blue marbles. With the data given we can set the following system of equations:
[tex]\begin{gathered} G+B=59, \\ G=B+23. \end{gathered}[/tex]Substituting the second equation in the first one, and solving for B we get:
[tex]\begin{gathered} (B+23)+B=59, \\ 2B+23=59, \\ 2B=59-23=36, \\ B=\frac{36}{2}=18. \end{gathered}[/tex]Substituting B=18 in the second equation on the board we get:
[tex]G=18+23=41.[/tex]Answer: The number of green marbles is 41, and the number of blue marbles is 18.