How do you solve this set of linear equations: $7x - 5y = 9; y = x - 1$ ?

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Answer 1 · 2016-11-28T07:08:38

${(x=2), (y=1) :}$

${(7x - 5y =9), (y = x - 1) :}$

Substitute $x-1$ for $y$ in the first equation

$7x - 5(x-1) = 9$

Multiply out the brackets

$7x - 5x + 5 = 9$

Subtract $5$ from both sides

$7x -5x = 4$

$2x = 4$

$x = 2$

Then

$y = x - 1$

$y = 2 - 1$

$y = 1$

To check, substitute the answers into the first equation

$7x - 5y = 9$

$14 - 5 = 9$

How do you solve this set of linear equations: 7x - 5y = 9; y = x - 17x - 5y = 9; y = x - 1?