Question

1. $x + 3y = 1$

+ $-3x - 3y = -15$
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Explanation:

Step1: Add the two equations

$$(x + 3y) + (-3x - 3y) = 1 + (-15)$$

Step2: Simplify to solve for x

$$x - 3x + 3y - 3y = -14$$
$$-2x = -14$$
$$x = \frac{-14}{-2} = 7$$

Step3: Substitute x=7 into first equation

$$7 + 3y = 1$$

Step4: Solve for y

$$3y = 1 - 7$$
$$3y = -6$$
$$y = \frac{-6}{3} = -2$$

Answer:

$x=7$, $y=-2$