We need to write teh equation for the line represented in the table, so we can take two any points from the table, we choose (0,20) and (8,0), so:
[tex]\begin{gathered} \text{The equation of a line with two points is:} \\ P_1=(t_1,V_1)=(0,20) \\ P_2=(t_2,V_2)=(8,0) \\ V-V_1=\frac{V_2-V_1}{t_2-t_1}(t-t_1) \\ V-20=\frac{0-20}{8-0}(t-0) \\ V=-\frac{20}{8}t+20 \\ V=-\frac{5}{2}t+20 \end{gathered}[/tex]
And the equation for the original line we can take two points from the graph, we choose (1, 25) and (2, 15), so:
[tex]\begin{gathered} P_1=(1,25),P_{}=(2,15) \\ V-25=\frac{15-25}{2-1}(t-1) \\ V=-\frac{10}{1}(t-1)+25 \\ V=-10t+10+25 \\ V=-10t+35 \end{gathered}[/tex]
