Applications with system of equations question

Hi Angel. You've been instructed to use symbols x and y.

Rate flying with the wind is x+y (time: 4 hr)

Rate flying against the wind is x-y (time: 4.25 hr)

Distance is 2720 mi each way.

d = (r)(t)

2720 = (x + y)(4)
2720 = (x - y)(4.25)

Solve the system.

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Thanks Otis, you're a lifesaver. 20 turned out to be the answer after I solved with the system you provided.
 
I solved with the system you provided.
Very good. Did you then consider what specifically went wrong the first time? (Hint: Look at your first line.) It's helpful for students to investigate and understand their mistakes -- that's part of the learning process.

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2720= 4(x+ y). Dividing both sides by 4, x+ y= 680.
2720= 4.25(x- y). Dividing both sides by 4.25, x- y= 640.

Since we are asked specically for the speed of the wind, y, subtract the second equation from the first, eliminating x- (x+ y)- (x- y)= x- x+ y+ y= 2y= 680- 640= 40 so y= 20 mph.
 
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