[tex]\bf \begin{array}{|cc|ll} \cline{1-2} \stackrel{Days}{d}&\stackrel{Price}{P}\\ \cline{1-2} 1&\$115\\ 2&\$150&\leftarrow 115+\stackrel{35(1)}{35}\\ 3&\$185&\leftarrow 115+\stackrel{35(2)}{35+35}\\ 4&\$220&\leftarrow 115+\stackrel{35(3)}{35+35+35}\\ d&&\leftarrow 115+35d\\ \cline{1-2} \end{array}~\hfill \stackrel{part~A}{P(d)=35d+115} \\\\\\ ~\hspace{34em}[/tex]
part B)
the slope is always in a linear equation, the coefficient of the independent variable, in this case namely "35".
35 or 35/1 dollars/day means
for every passing day the car is rented out, the charge is $35, so if you rent the car "d" days, you'll be charged 35d.
