Answer:
P = 500 - 40t
Step-by-step explanation:
P is the number of pages has left to read
the initial value is 500
the rate of change is 40 pages per hour (t)
you must subtract from the initial
The equation is P = initial - 40t or
P = 500 - 40t
To check, at 0 hours you have 500 pages or P = 500 - 40(0)
at 10 hours, P = 500 - 40(10) = 500 - 400 = 100