Let
P-------> the number of pages Margaret has left to read
d-------> the number of days Margaret has been reading
we know that
\(P=276-35d\)
This is a linear equation
where
\(-35\) ------> is the slope of the equation
represent \(35\frac{pages\ read}{day}\)
\(276\) ------> the total number of pages in the book
\(35d\) ------> the number of pages she has read during d days
the graph in the attached figure
