Updating the last row of a column by adding numeric value to [table2] with data coming from [table1]

[Keven11]

Hello, 

I am working on 2 tables where I want the last record in [table 2] to be added by the record of [table 1]  every time a new record is coming to the [table 1]. Does anyone know the expression(s) to be used for such a task? 

Highly appreciate your help!