Question

3.
$9x - 4y = -20$
$-3x + 4y = 20$

Explanation:

Step1: Add the two equations

$$(9x - 4y) + (-3x + 4y) = -20 + 20$$
Simplify the left and right sides:
$$6x = 0$$

Step2: Solve for x

$$x = \frac{0}{6} = 0$$

Step3: Substitute x=0 into first equation

$$9(0) - 4y = -20$$
Simplify:
$$-4y = -20$$

Step4: Solve for y

$$y = \frac{-20}{-4} = 5$$

Answer:

$x=0$, $y=5$