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How do i use substitution to solve each system?

y= 0.8x + 7.2
20x + 32y=48

  • algebra -

    I would rearrange them to know what I had.
    0.8x - y = -7.2
    20x +32y = 48

    Then I would consider taking out the largest factor I could in the second equation. That would be a factor of 4.

    For solving by substitution, I would solve the first equation for y which would be -y = -7.2 - 0.8x or
    y = 7.2+0.8x

    Substitute this value for y into the second equation and go from there.

  • algebra -

    your first equation tells you what y is, so sub that into the second

    20x + 32(.8x+7.2) = 48

    solve for x, then sub that x value back into the first equation to get y.

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