$subtract from fixed value in mongodb code example
Example: mongodb subtract dates
db.sales.aggregate( [ { $project: { item: 1, total: { $subtract: [ { $add: [ "$price", "$fee" ] }, "$discount" ] } } } ] )db.sales.aggregate( [ { $project: { item: 1, total: { $subtract: [ { $add: [ "$price", "$fee" ] }, "$discount" ] } } } ] )