I have some red, green beans and bottles. If I put \( 5 \) beans into each bottle, nothing will be left. Instead, if I put \( 3 \) red beans into each bottle, I will have \( 1 \) red bean left. However, if I put \( 3 \) green beans into each bottle, I will have \( 2 \) green beans and \( 2 \) bottles left.
Express red beans as \( x \), green beans as \( y \), bottles as \( z \),
find the value of \( xyz-xy \)