Combine duplicate rows on column1 sum column2

I have the following data.

Id      ParentId    ProductId   Quantity 215236  19297       16300319    60 215221  19297       16314611    6 215234  19297       16314670    1    <- Duplicate productid 215235  19297       16314670    2    <- Duplicate productid 215195  19297       16314697    20 215205  19297       16321820    75 215216  19297       16329252    10 215233  19297       16331834    9 215224  19297       16519280    40 

Selecting unique records is easy. Or grouping the data on ProductId is also possible. I need a result that only contains a unique Product Id with the same parentid and the quantities summed up.

The result should look like this.

Id      ParentId    ProductId   Quantity 215236  19297       16300319    60 215221  19297       16314611    6 215234  19297       16314670    3 215195  19297       16314697    20 215205  19297       16321820    75 215216  19297       16329252    10 215233  19297       16331834    9 215224  19297       16519280    40 

The quantities of the duplicates

215234  19297       16314670    1    <- Duplicate productid 215235  19297       16314670    2    <- Duplicate productid 

should result in

215234  19297       16314670    3