How do you solve 3x + y = 2 and 4x + y = 20?

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Answer 1 · 2015-10-13T07:49:59

$color(green)(x = 18$
$color(green)(y = -52$

$3x + y = 2$ --------(1)
$4x + y = 20$ ------(2)

To eliminate $y$ we can subtract (1) from (2)

$(4x+y) - (3x+y) = 20 -2$

$(4x - 3x) + (y - y) = 18$

$color(green)(x = 18$

Substituting $x = 18$ in (1) we get

$3(18) + y = 2$

$54 + y = 2$

Transposing 54 to the right hand side, we get

$y = 2 - 54$

$color(green)(y = -52$