Answer:
Number of pages read on sunday night = 26
Explanation:
Let the number of pages read on sunday night be p.
Reese read twice as many pages saturday night than she read sunday night.
Number of pages read on saturday night = 2 x p = 3p.
she read a total of 78 pages over the weekend.
Number of pages she read over the weekend = 2p + p = 3p = 78
Simplifying
p = 26
Number of pages read on sunday night = 26