How do you solve $y = 2 x + 9$ $y=2x+9$ and $y = 9 x + 10$ $y=9x +10$ using substitution?

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Answer 1 · 2018-04-26T22:49:44

$x = - \frac{1}{7}$ $x = -1/7$ and $y = 8 \frac{5}{7}$ $y = 8 5/7$

Take one y value and substitute it as the y value in the other equation.

Let's use $y = 2 x + 9$ $y = 2x + 9$ to substitute in the other equation

$2 x + 9 = 9 x + 10$ $2x + 9 = 9x + 10$

Subtract 2x from both sides, then subtract 10 from both sides.

$9 = 7 x + 10$ $9 = 7x + 10$
$- 1 = 7 x$ $-1 = 7x$

Divide both sides by 7

$- \frac{1}{7} = x$ $-1/7 = x$

Now apply your new x value to the first equation, $y = 2 x + 9$ $y = 2x + 9$

$y = (2 \cdot - \frac{1}{7}) + 9$ $y = (2*-1/7) + 9$
$y = - \frac{2}{7} + 9$ $y = -2/7 + 9$
$y = 8 \frac{5}{7}$ $y = 8 5/7$

How do you solve y=2x+9y=2x+9y=2x+9 and y=9x +10y=9x+10y=9x +10 using substitution?