Question

 A man can row 30 km upstream and 45 km downstream in 7 hours. also, he can row 20 km upstream and 34 km downstream in 5 hours. find the speed of the man in still water and the speed of the current. *​

Answer 1

Answer:

30/D + 20/U=4-----------------------------EQUATION 1 45/D + 40/U=7-----------------------------EQUATION 2

EQUATION 1x2 - EQUATION 2 MIDDLE TERM CANCEL SO WE GET 15/D=1 D=15 NOW PUT THE VALUE OF D IN EQUATION 1 30/D+20/U=4 I.E 2+20/U=4 U=10 I.E D=15, U=10 M+S=15 EQU 3 D=M+S M-S=10 EQU 4 U=M-S SOLVE EQU 3 & EQU 4 BY LINEAR EQUATION S CANCELED SO WE GET M=12.5 WHICH IS MAN SPEED IF WE WANT THEN WE GET THE VALUE OF STREAM SPEED ALSO I.E S=15-12....