546
google search
Google search results:
1: https://brainly.com/question/3267105
++++++++++++++++
2: https://www.quora.com/A-man-rows-20-km-downstream-in-1-hour-and-40-minutes-and-12-km-upstream-in-1-hr-and-30-minutes-What-is-the-speed-of-the-man-in-still-water-and-also-speed-of-water
++++++++++++++++
3: https://www.toppr.com/ask/en-au/question/a-man-complete-a-journey-in-10-hours-he-travels-first-half-of-the-journey/
++++++++++++++++
4: https://studysite.org/Discuss/Question/a_man_rows_20km_upstream_in_150_minutes_if_the_speed_of_the_stream_is_45_kmph_find_his_speed_in_still_water-30205022.htm
++++++++++++++++
5: https://www.kodnest.com/exam/boats-streams-easy/53/
++++++++++++++++
6: https://www.competoid.com/quiz_answers/14-0-20006/Question_answers/
++++++++++++++++
7: https://www.easytutorial.in/question/44331
++++++++++++++++
8: http://pchshonorsmath3.weebly.com/uploads/8/7/2/6/87263872/applicationsnoteskey.pdf
++++++++++++++++