Math help

Solve using substitution
3x - 9y = 3
6x - 3y = -24

Solve using elimination
y - 1/2x = 6
2x + 6y = 19

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asked by Josh
  1. divide first equation by 3
    x - 3 y = 1
    so
    x = (3y+1)
    substitute that for x in the second equation after dividing the second equation by 3
    2 (3y+1) - y = -8
    6 y + 2 - y = -8
    5 y = -10
    y = -2
    then x -3(-2) = 1
    x + 6 = 1
    x = -5

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    posted by Damon
  2. y - 1/2x = 6
    is
    -x + 2 y = 12
    2x + 6y = 19
    multiply first eqn by 2 again
    -2x + 4 y = 24
    +2x + 6 y = 19
    ============== add
    0 + 10 y = 43
    y = 4.3
    4.3 -.5 x = 6
    .5 x = -1.7
    x = - 3.4

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    posted by Damon

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