Jean read 4 books in 1 h 32 min. She took the same amount of time to read each of the first 3 books. She took 40 min longer to read the fourth book than each of the first 3 books. She finished reading all the books at 20 45. What time did she start reading the fourth book?
Duration that Jean took to read the first book = 1 u
Duration that Jean took to read the second book = 1 u
Duration that Jean took to read the third book = 1 u
Duration that Jean took to read the fourth book = 1 u + 40 min

Total duration that Jean took to read the four books 
= 1 u + 1 u + 1 u + 1 u + 40 min
= 4 u + 40 min

4 u + 40 min = 1 h 32 min
4 u = 92 min - 40 min
4 u = 52 min  

1 u = 52 min ÷ 4 = 13 min

Duration that Jean took to read the fourth book
= 13 min + 40 min
= 53 min
= 53 min

53 min before 20 45: 19 52

Time that Jean started to read the fourth book = 19 52

Answer(s): 19 52