Answer:
Domain={R} Range={R}
Explanation:
The function is a lineal function and every lineal function´s domain and rage is the set real numbers.
In order to sketch the function you only need to know 2 points od the function and unite them with a straight line. You can know them replacing x for a number and calculating f(x). I did it for x=0 and x=3
![f(x=0)=(1)/(3) *0+3=3\\f(x=3)=(1)/(3) *3+3=4\\](https://img.qammunity.org/2020/formulas/mathematics/college/fa83o3qtom0vo0h1p7f37zc685f6an8olc.png)
Now you have defining 2 point
P1=(0,3)
P2=(3,4)
I added an image of the function sketched