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Question 314880: I need help on solving by linear equation.
4x-5y=20 and 5x+5y=70 I need to show work.
Answer by CharlesG2(834)   (Show Source):
You can put this solution on YOUR website! I need help on solving by linear equation.
4x-5y=20 and 5x+5y=70 I need to show work.
there are a few ways you can do this, solving for y on both and then setting equations equal is one, matrixes is another, elimination and substitution is yet another
4x -5y = 20
5x +5y = 70 (notice the coefficients on the y's, they are opposites, add the 2 equations together)
9x = 90
x = 10, we now know x
subsitute x into one of the equations and solve for y
4(10) - 5y = 20
40 - 5y = 20
-5y = -20
y = 4
we could have used the other equation as well
5(10) + 5y = 70
50 + 5y = 70
5y = 20
y = 4
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