This is false.
The f(3x) means you are multiplying the input 'x' by 3 before plugging into the equation.
3f(x) means you are going to multiply your answer (output) by 3 after you've plugged the input value in and gotten the output.
John's. Find the first common multiple of both denominators, in this case it's going to be ten, then the number you had to multiply to change these numbers to the common multiply you do to the numerators. so it works out like so:
Deena has a bottle of 4/10
John has a bottle of 25/10 or 2 1/2 (simplified)