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How do you solve $2 x + 7 y = 15$ $2x+7y=15$ and $x = 3 - 2 y$ $x=3-2y$ using substitution?

1 Answer

Jun 4, 2016

$y = 3$ $y=3$

Explanation:

As $x = 3 - 2 y$ $x=3-2y$ , we can replace $x$ $x$ in the other equation with this, turning it into

$2 (3 - 2 y) + 7 y = 15$ $2(3-2y)+7y=15$ which when expanded

$6 - 4 y + 7 y = 15$ $6-4y+7y=15$

$6 + 3 y = 15$ $6+3y=15$

$3 y = 9$ $3y=9$

$y = 3$ $y=3$

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