using these linear equations:
2x + 5y= 6
3x + 4y= 8
I have to write these in the form AX= B where A, X and B are matrices.
how do I do this??

I think your initial equations will transform into this (if this helps you) but I haven't done matrices in a while:
\left[ \begin{array}
2 \\
3
\end{array} \right] x +
\left[ \begin{array}
5 \\
4
\end{array} \right] y =
\left[ \begin{array}
6 \\
8
\end{array} \right]