solution:
The difference of a number and 9 is (x−9).
Twice the difference means 2(x−9).
We know that the answer to this is 2, so as an equation:
2 ( x - 9 )
If you solve it we would have:
x - 9= 1
x= 1 + 9
x= 10
The difference between 10and9 is 1 and twice 1 is 2.
The number is correct.
= 2x - 9