the sum of two numbers is 21. the larger number is 6 less than twice the smaller number. find the two numbers

let x represent the smaller number.
larger number=2x-6
2x-6+x=21
3x-6=21
3x=21+6
3x=27
x=9
the smaller number is 9
the bigger number is 2(9)-6=18-6=12.