[tex] \text {Hello,Hope you are fine!}[/tex]
Let the required mass be x.
As we know that 1kg is equal to 1000g.
So equation can be made as following:-
350g+x=1000g
➛ x=1000g-350g
➛ x=650g
Hence your answer is 650g.
[tex] \text{Keep learning,Good luck!}[/tex]