Answer: 7
let x be the number
2(-9 + x) = x - 11
-18 + 2x = x - 11
2x - x = -11 + 18
x = 7
Suppose that x is the number we want :
- 9 added to it means :
[tex]x + ( - 9) = x - 9[/tex]
And sum is doubled means :
[tex]2 \times (x - 9)[/tex]
The result is 11 less than the number which means :
[tex]2 \times (x - 9) = x - 11[/tex]
Now let's find the x ...
[tex]2x - 18 = x - 11[/tex]
Add both sides 18
[tex]2x - 18 + 18 = x - 11 + 18[/tex]
[tex]2x = x + 7[/tex]
Subtract both sides x
[tex]2x - x = x + 7 - x[/tex]
[tex]2x - x = x - x + 7[/tex]
[tex]x = 7[/tex]
Thus that number is 7
