Answer :
You need to solve a system comprised of 3 equations.
1) k+m+n=1500
2) m=3n
3) k=2n
Replace equations 2) and 3) in 1) => 2n+3n+n=1500 => 6n=1500 => n=250
By reaplacing n in 2) => m=3*250=750
In 3) => k=2*250=500
1) k+m+n=1500
2) m=3n
3) k=2n
Replace equations 2) and 3) in 1) => 2n+3n+n=1500 => 6n=1500 => n=250
By reaplacing n in 2) => m=3*250=750
In 3) => k=2*250=500