Let us assume the number be x.
The quotient of a number and 2 can be expressed as : x/2.
The difference of the number doubled and 3 can be expressed as : 2x -3.
The quotient of a number and 2 is the same as the difference of the number doubled and 3.
Therefore,
x/2 = 2x-3.
On cross multiplication, we get
x = 2(2x-3).
x = 4x -6
Subtracting 4x from both sides, we get
x-4x = 4x-4x -6
-3x = -6.
Dividing both sides by -3, we get
-3x/-3 = -6/-3.
x = 2.
Therefore, unknown number is 2.