{string} Items = …;
tuple Item {
int weight;
int classification_1;
int classification_2;
…}

dvar int a[Items] in 0..1;

Ball_object; 23; 1; 2; …

Subjected to {
    Forall ( i_1 in Items )
    ctItemRatio:
    (Item[i_1].weight * a[i_1]) / (sum (I in Items) (Item[i].weight * a[i])) <= 0.1;
}