Database
[{city:"Mumbai",meta:{luggage:2,scanLuggage:1,upiLuggage:1},cash:10},{city:"Mumbai",meta:{luggage:4,scanLuggage:3,upiLuggage:1},cash:24},]
Query
db.collection.aggregate([{$match:{city:"Mumbai"}},{$project:{city:1,"meta.luggage":1,"meta.scanLuggage":1,"meta.upiLuggage":1}},{$group:{_id:"$city",luggage:{$sum:"$meta.luggage"},scanLuggage:{$sum:"$meta.scanLuggage"},upiLuggage:{$sum:"$meta.upiLuggage"}}}])