Casey is reading a book for a book report. at 3: 30 p. m., he started reading where he had left off the day before. at 5: 30 p. m. he was on page 160. at 8: 00 p. m. he was on page 280. if reading the book is modeled by a linear function, what page did casey start on at 3: 30 p. m.?

To find the time Casey read today, 5:30 from 8:00.
8:00 - 5:30 = 2:30
Casey

To find the number of pages Casey read today subtract the page number he started reading on to the page he stopped on.
280 - 160 = 120
Casey read 120 pages today.

Now you need to find how many pages Casey read in one hour.

If Casey read 120 pages in 2.5 hours, you can find how many pages he read in one hour by dividing 120 by 2.5.
120 ÷ 2.5 = 48.
Casey read 48 pages in one hour.

Casey was on page 160 at 5:30, and you need to find what page he was on at 3:30. Since Casey read for 2 hours before he reached page 160, you need to subtract 2 hours worth of reading from that number.

160 - (2×48)
160 - 96
64

Casey was on page 64 at 3:30 pm today.