SOLUTION: jessica drove her speedboat upriver this morning. it took her 1 hour going upriver and 54 minutes going downriver. if she traveled 36 miles each way, what would have been the rate

Question 538068: jessica drove her speedboat upriver this morning. it took her 1 hour going upriver and 54 minutes going downriver. if she traveled 36 miles each way, what would have been the rate of the boat in still water and what was the rate of the current in miles per hour?
Answer by mananth(16946) (Show Source): You can put this solution on YOUR website!
Boat speed =x mph
current speed =y mph
against current x-y 1.00 hours
With current x+y 0.90 hours

Distance = same= 36 miles
t=d/r
36 / ( x - y )= 1.00
1 ( x - y ) = 36.00
1 x -1 y = 36 ....................1
36 / ( x + y )= 0.90
0.90 ( x + y ) = 36
0.90 x + 0.90 y = 36 ...............2
Multiply (1) by 0.90
Multiply (2) by 1.00
we get
0.9 x + -0.9 y = 32.4
0.9 x + 0.9 y = 36
1.8 x = 68.4
/ 1.8
x = 38 mph

plug value of x in (1)
1 x -1 y = 36
38 -1 y = 36
-1 y = 36 -38
-1 y = -2
y = 2 mph
Boat 38 mph
current 2 mph

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