Answers

2015-09-09T18:39:16+05:30
Take speed of boat in still water =xkm/hr nd in stream water =ykm/h fir upstream speed will be x-y nd for downstream it will be x+y km/hr. As time =dist/speed for 1st case 12/x-y +40/x+y =8 now let x-y =p x+y=q 12p+40q=8 ~ly for 2nd case it will be 16/x-y+32/x+y=8 =>16p+32q=8 wth any metho
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It was not completed fully here is th ans wth any method substitution,elimination or cross multiplication you will get value of p nd q it's p=1/4 nd q=1/8 as p=1/x-y 1/8=1/x-y ie x-y=8 ~ly q=1/x+y nd x+y =4 with elimination you will get value of x nd y x=6 y=2 speed of boat in still water = 6km/hr nd in stream water =2km/hr