What is the average rate of change please write your answer as an integer or simplify fraction

Given:
f(x)=6x+3
Required:
To calculate the average rate
Explanation:
[tex]\begin{gathered} Average\text{ rate of change} \\ \\ y=6x+3\text{ at \lparen x=5\rparen} \\ \\ y=6(5)+3=33 \end{gathered}[/tex][tex]\begin{gathered} y=6x+3\text{ at\lparen x=10\rparen} \\ \\ y=6(10)+3 \\ \\ y=63 \end{gathered}[/tex][tex]\begin{gathered} average\text{ }rate\text{ }of\text{ }change \\ \\ y=63-33 \\ \\ y=30 \end{gathered}[/tex]Required answer:
30