First we need to find the equation, so we need to calculate the slope
[tex]m=\frac{y_2-y_1}{x_2-x_1}[/tex]where
(5,30)=(x1,y1)
(10,0)=(x2,y2)
these points are part of the line
[tex]m=\frac{0-30}{10-5}=\frac{-30}{5}=-6[/tex]then we need the y-intercept, in this case, is when the value of B when t is 0
in our case is 60
therefore the equation is
[tex]B=-6t+60[/tex]the slope as we calculate previously is -6 which revels