Verona is solving the equation –3 4x = 9. in order to isolate the variable term using the subtraction property of equality, which number should she subtract from both sides of the equation? a: –4b: –3c: 3d: 4

I believe that the original expression is:
-3+4x = 9

Now, we want to isolate the variable terms. This means that we need to remove the (-3) that is present with the 4x.
To do this, we can simply add (+3) to both sides of the equation as the result on the side of the variable term will be: -3+3+4x = 4x which is the purpose of the isolation.

The new expression will be:
4x = 9+3 = 12

The answe is:
c:3

Where is the problem