The value of the smaller number, y, is equal to 9.
The value of the larger number, x, is equal to 12.
x + y = 21
x = 2y - 6
We have a value for x, so we can plug it into the original equation to solve for y.
2y - 6 + y = 21
Combine like terms.
3y - 6 = 21
Add 6 tot both sides.
3y = 27
Divide both sides by 3.
y = 9
Now that we have a value for x, we can plug it into the 2nd equation to solve for x.
x = 2(9) - 6
x = 18 - 6
x = 12