[{_id:1,task_number:1,description:"Clean Bathroom",customer:"Walmart",users_worked:[{user:"Jonny",hours:1},{user:"Cindy",hours:1}],supplies_used:[{item_code:"LD4949",description:"Liquid Detergent",quantity:1}]},{_id:2,task_number:2,description:"Stock Cheeses",customer:"Walmart",users_worked:[{user:"Mark",hours:3.0},{user:"Shelby",hours:2.0}],supplies_used:[]}]

db.collection.aggregate([{$project:{task_number:1,description:1,customer:1,users:{$reduce:{input:"$users_worked",initialValue:"",in:{$concat:["$$value",", ","$$this.user"]}}},users_worked:{$sum:"$users_worked.hours"},quantity:{$sum:"$supplies_used.quantity"}}}])