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If 725x + 727y = 1500 and 729x + 7y = 1508, what is the value of x - y?

 Apr 21, 2022
 #1
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the answer is 271404/131227

 Apr 21, 2022
 #2
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\(\begin{cases}725x + 727y = 1500 \text{ --- }(1)\\729x + 7y = 1508\text{ --- }(2)\end{cases}\)

 

Subtract (1) from (2) to get 

\(4x - 720y = 8\\ x - 180y = 2\text{ --- }(3)\)

 

Now, solve the system formed by equations (2) and (3) using method of elimination, and you will get \((x, y) = \left(\dfrac{271454}{131227}, \dfrac{50}{131227}\right)\)

 

Therefore, x - y = \(\dfrac{271404}{131227}\), as robloxDying suggested.

 Apr 22, 2022
 #3
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I think that that 7 in the 7y term looks incongruous.

I suspect a typo !

 Apr 22, 2022

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