Section 6.8: Exercises 36, 54, 64

36). Upstream downstream. Junior's boat will go 15 miles per hour in still water. If he can go 12 miles downstream in the same amount of time as it takes to go 9 miles upstream, hen what is the speed of the current?

Speed of current x mph

Speed when downstream (15x)mph

Speed when upstream (15-x)mph

Distance

Now according to the question both time are same so

The speed of the current will be mph

54). Big Plane. A six passenger plane cruises at 180 mph in calm air. If the plane flies 7 miles with the win in the same amount of time as it flies 5 miles against the wind, then what is the wind speed?

Speed of wind x mph

Speed of plane in the direction of wind (180 x) mph

Speed against direction (180-x) mph

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