# How do you solve 3x+7y=10 and x=18-6y using substitution?

$x = - 6$
$y = 4$

#### Explanation:

Solution by substitution
$3 x + 7 y = 10 \text{ }$first equation
$x = 18 - 6 y \text{ }$second equation

Use the second equation into the first equation

$3 x + 7 y = 10 \text{ }$first equation

Now use the second in place of x

$3 \left(18 - 6 y\right) + 7 y = 10 \text{ }$first equation

$54 - 18 y + 7 y = 10$

$- 18 y + 7 y = 10 - 54$

$- 11 y = - 44$

$y = \frac{- 44}{- 11}$

$y = 4$

Use now the second equation $x = 18 - 6 y \text{ }$second equation and $y = 4$ to solve for $x$

$x = 18 - 6 y \text{ }$second equation

$x = 18 - 6 \left(4\right) \text{ }$

$x = 18 - 24$

$x = - 6$

God bless....I hope the explanation is useful.