Solution:
The rate of change, m, is;
[tex]\begin{gathered} m=\frac{d_2-d_1}{t_2-t_1} \\ \\ \text{ Where }d=distance,t=time \end{gathered}[/tex]Thus;
[tex]\begin{gathered} (1,10),(3,30) \\ \\ m=\frac{30-10}{3-1} \\ \\ m=\frac{20}{2} \\ \\ m=10 \end{gathered}[/tex]ANSWER: (D) 10 feet per minute