[{"_id":{"$oid":"64a5a396ec152ab4f5e1c60c"},"firstName":"Ram","lastName":"Shayam","email":"abc@123.com","transactions":[{"amount":22,"date":"21/7"},{"amount":12,"date":"21/7"},{"amount":50,"date":"19/7"},{"amount":100,"date":"19/7"}]}]

db.collection.aggregate([{$match:{firstName:"Ram"}},{$unwind:"$transactions"},{$match:{"transactions.date":{$eq:"21/7"}}},{$group:{_id:"$_id",list:{$push:"$transactions"},total:{$sum:"$transactions.amount"}}}])