Sarah read 3 books in 2 h 27 min. She took the same amount of time to read each of the first 2 books. She took 30 min longer to read the third book than each of the first 2 books. She finished reading all the books at 18 46. What time did she start reading the third book?
Duration that Sarah took to read the first book = 1 u
Duration that Sarah took to read the second book = 1 u
Duration that Sarah took to read the third book = 1 u + 30 min

Total duration that Sarah took to read the three books 
= 1 u + 1 u + 1 u + 30 min
= 3 u + 30 min

3 u + 30 min = 2 h 27 min
3 u = 147 min - 30 min
3 u = 117 min  

1 u = 117 min ÷ 3 = 39 min

Duration that Sarah took to read the third book
= 39 min + 30 min
= 69 min
= 1 h 9 min

1 h 9 min before 18 46: 17 37

Time that Sarah started to read the third book = 17 37

Answer(s): 17 37