Gabby read 3 books in 2 h 6 min. She took the same amount of time to read each of the first 2 books. She took 36 min longer to read the third book than each of the first 2 books. She finished reading all the books at 18 45. What time did she start reading the third book?
Duration that Gabby took to read the first book = 1 u
Duration that Gabby took to read the second book = 1 u
Duration that Gabby took to read the third book = 1 u + 36 min

Total duration that Gabby took to read the three books 
= 1 u + 1 u + 1 u + 36 min
= 3 u + 36 min

3 u + 36 min = 2 h 6 min
3 u = 126 min - 36 min
3 u = 90 min  

1 u = 90 min ÷ 3 = 30 min

Duration that Gabby took to read the third book
= 30 min + 36 min
= 66 min
= 1 h 6 min

1 h 6 min before 18 45: 17 39

Time that Gabby started to read the third book = 17 39

Answer(s): 17 39