It is given in the question that
Ben has a collection of 812 stamps. He gives his brother 345 stamps.
And we have to find how many stamps does Ben have left .
Let x stamps are left.
So we have
[tex]x+345=812[/tex]
Subtracting 345 from both sides
[tex]x+345-345 = 812-345[/tex]
[tex]x = 467[/tex]
Therefore after giving 345 stamps to his brother, 467 stamps are left .