[{"_id":ObjectId("5ff4b728b6af610f0851d2a6"),"totalScore":500,"totalCompleted":100,"monthly":[{year:2021,month:7,attempted:10,completed:5,score:20,},{year:2021,month:8,attempted:10,completed:5,score:20,}],},{"_id":ObjectId("5ff4b728b6af610f0851d2a7"),"totalScore":305,"totalCompleted":55,"monthly":[{year:2021,month:6,attempted:15,completed:8,score:25,},{year:2021,month:7,attempted:2,completed:1,score:15,}],}]

db.collection.find({},{totalScore:1,"monthly":{$elemMatch:{year:2021,month:8,},},})