Hello there here is the problem you gave us
[tex]y=2x,x+y=9[/tex]
You want to us to solve this by substitution,
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- [tex]x= \frac{1}{2}y[/tex]
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we can substitute [tex]y[/tex] for [tex]2x[/tex] and get the equation
[tex]x+2x=9[/tex], do the simple algebra and we get that [tex]x=3[/tex], remember though [tex]y=2x[/tex], plug in the value that [tex]x=3[/tex] and get that [tex]y=6[/tex]
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[tex]{\huge{\boxed{\mathfrak{Answer}}}[/tex]
Have a good day :) !
