Question

use substitution to solve the system.
$2x + 5y = -18$
$x = 2y + 9$
$x = \square$
$y = \square$

Explanation:

Step1: Substitute $x$ into first equation

Substitute $x=2y+9$ into $2x+5y=-18$:
$2(2y+9)+5y=-18$

Step2: Expand and simplify

Expand the left-hand side:
$4y+18+5y=-18$
Combine like terms:
$9y+18=-18$

Step3: Solve for $y$

Subtract 18 from both sides:
$9y=-18-18=-36$
Divide by 9:
$y=\frac{-36}{9}=-4$

Step4: Solve for $x$

Substitute $y=-4$ into $x=2y+9$:
$x=2(-4)+9=-8+9=1$

Answer:

$x = 1$
$y = -4$