In reply to sharvil111:
You can also convert the expression to integral by writing
constraint subset_c {foreach(subset) subset[I] inside {[15 * num_fruits[I]/100 : 75 * num_fruits[I]/100]}; }
But another problem is you are not allowed to use a random variable as an array select
fruit_num_array[fruits[j]]
cannot be used. You’ll need to nest another foreach (fruit_num_array[k])