[tex]beginning:\\
3x-\ apple\ juice\\2x-\ orange\ juice\\\\
after\ delling\ 64\ bottles\ of\ apple\ juice:\\
y-\ apple\ juice\\
6y-\ orange\ juice\\\\
3x-64=y\\
2x=6y\ \ \ | divide\ by\ 2\\
x=3y\\\\
3*3y-64=y\\
9y-64=y\ \ \ | subtract\ 9y\\
-64=-8y\ \ \ | divide\ by\ -8\\
y=8\\\\
At\ the\ end\ he\ has\ 8\ apple\ juice\ and\ 48\ orange\ juice.
[/tex]