How do you solve the system of equations $x - 7 y = 21$ $x- 7y = 21$ and $2 x - 7 y = 28$ $2x - 7y = 28$ ?

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How do you solve the system of equations $x - 7 y = 21$ $x- 7y = 21$ and $2 x - 7 y = 28$ $2x - 7y = 28$ ?

1 Answer

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Answer 1 · 2018-03-26T04:46:57

$x = 7$ $x = 7$ and $y = - 2$ $y = -2$

Explanation:

$x - 7 y = 21$ $x-7y = 21$
$2 x - 7 y = 28$ $2x - 7y = 28$

Subtracting the second equation from the first equation:
$2 x - 7 y - (x - 7 y) = 28 - 21$ $2x - 7y - (x - 7y) = 28-21$
$2 x - 7 y - x + 7 y = 7$ $2x - 7y -x + 7y = 7$
$x = 7$ $x = 7$

Plugging in $7$ $7$ for $x$ $x$ in the first equation:
$7 - 7 y = 21$ $7-7y = 21$
$7 = 21 + 7 y$ $7 = 21 + 7y$
$7 y = 7 - 21$ $7y = 7-21$
$7 y = - 14$ $7y = -14$
$y = - \frac{14}{7}$ $y = -14/7$
$y = - 2$ $y = -2$

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How do you solve the system of equations $x - 7 y = 21$ $x- 7y = 21$ and $2 x - 7 y = 28$ $2x - 7y = 28$ ?

1 Answer

Explanation:

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Science

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Humanities

... and beyond

How do you solve the system of equations x−7y=21x- 7y = 21 and 2x−7y=282x - 7y = 28?

1 Answer

Explanation:

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How do you solve the system of equations $x - 7 y = 21$ $x- 7y = 21$ and $2 x - 7 y = 28$ $2x - 7y = 28$ ?