[{"Scores":10},{"Scores":20}]

db.collection.find({$expr:{$or:[{/** $eq: [<score_min>, -1]*/$eq:[15,-1]},{$and:[{/** $gte: ["$Scores", <score_min>]*/$gte:["$Scores",15]},{$lte:[/** $gte: ["$Scores", <score_max>]*/"$Scores",25]}]}]}})