Question

tuesday:
$y=4x+6$
$-5x-y=21$
thursday:

Explanation:

Step1: Substitute $y$ into second equation

Substitute $y=4x+6$ into $-5x-y=21$:
$$-5x-(4x+6)=21$$

Step2: Simplify and solve for $x$

Expand and combine like terms:
$$-5x-4x-6=21$$
$$-9x-6=21$$
$$-9x=21+6$$
$$-9x=27$$
$$x=\frac{27}{-9}=-3$$

Step3: Solve for $y$ using $x=-3$

Substitute $x=-3$ into $y=4x+6$:
$$y=4(-3)+6=-12+6=-6$$

Answer:

$x=-3$, $y=-6$