Final answer:
The function representing the number of pages Shryia has left to read at a given time is P(t) = 480 - 52t, considering she reads at a constant rate of 52 pages per hour.
Step-by-step explanation:
Shryia read a 480-page book in one session at a constant rate. Since P(t) represents the number of pages she has left to read at time t, after 1.5 hours, she had 402 pages left. To find the rate at which she reads, we can see that in 1.5 hours, she read 480 - 402 = 78 pages. Thus, her reading rate is 78 pages per 1.5 hours, or 52 pages per hour.
At time t=0, the book is completely unread, meaning P(0) = 480 pages. Her reading rate is constant, so the function is linear: for every hour that passes, 52 more pages are read. Therefore, the number of pages left, P(t), decreases by 52 for each hour. The function P(t) can then be defined as:
P(t) = 480 - 52t