Question

the equations were multiplied by constants and added together to determine that the value of x in the system of equations is -20. \\\\ $\frac{1}{5}x - \frac{1}{3}y = -1$ \\\\ $-\frac{3}{4}x + \frac{1}{3}y = 12$ \\\\ what is the value of y? \\\\ $\circ$ -15 \\\\ $\circ$ -9 \\\\ $\circ$ 9 \\\\ $\circ$ 15

Explanation:

Step1: Substitute $x=-20$ into first equation

$\frac{1}{5}(-20) - \frac{1}{3}y = -1$

Step2: Simplify the left term

$-4 - \frac{1}{3}y = -1$

Step3: Isolate the $y$-term

$-\frac{1}{3}y = -1 + 4$
$-\frac{1}{3}y = 3$

Step4: Solve for $y$

$y = 3 \times (-3)$

Answer:

-9