Equivalant MongoDB query of MySQL date query with arithmetic operations
The equivalent MongoDB Query is

 db.temp_table.aggregate([{$project:{field1:1,field2:1,hours:{$abs:{$divide:[{$subtract:[ISODate(),"$datefield"]},3600000]}},time:{$sum:[{$multiply:["$field1","$field2","$field2"]},{$multiply:"$field3",{$divide:[1,{$abs:{$divide:[{$subtract:[ISODate(),"$datefield"]},3600000]}}]}]}]}}}])


Fields to be shown can be added as per the requirement.