Question

1. marco wrote the following system on the board: 3x - 4y=-18 8x - 4y=-28 what is the solution to the equation? (-2,3) (8,-3) (-3,8) (3,-2)

Explanation:

Step1: Subtract the second - equation from the first

Subtract $3x - 4y=-18$ from $8x - 4y=-28$ to eliminate $y$.
$(8x - 4y)-(3x - 4y)=-28-(-18)$
$8x - 4y - 3x + 4y=-28 + 18$
$5x=-10$

Step2: Solve for $x$

Divide both sides of $5x=-10$ by 5.
$x=\frac{-10}{5}=-2$

Step3: Substitute $x = - 2$ into the second equation

Substitute $x=-2$ into $3x - 4y=-18$.
$3\times(-2)-4y=-18$
$-6-4y=-18$

Step4: Solve for $y$

Add 6 to both sides: $-4y=-18 + 6=-12$.
Divide both sides by - 4: $y=\frac{-12}{-4}=3$

Answer:

$(-2,3)$