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How do you solve by substitution $y = x + 3$ $y=x+3$ and $5 x + y = 9$ $5x+y=9$ ?

1 Answer

Apr 13, 2018

$x = 1$ $x=1$
$y = 4$ $y=4$

Explanation:

$y = x + 3$ $y=x+3$ --- (1)
$5 x + y = 9$ $5x+y=9$ --- (2)

Sub (1) into (2)

$5 x + x + 3 = 9$ $5x+x+3=9$

$6 x = 6$ $6x=6$

$x = 1$ $x=1$ --- (3)

Sub (3) into (1)

$y = 1 + 3$ $y=1+3$

$y = 4$ $y=4$

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