Question

12x=76-20y
8x=84-20y

Answer 1

x = -2, y = 5 → (-2, 5)

Explanation:

`\left\{\begin{array}{ccc}12x=76-20y&\text{change the signs}\\8x=84-20y\end{array}\right\\\\\underline{+\left\{\begin{array}{ccc}-12x=-76+20y\\8x=84-20y\end{array}\right}\qquad\text{add both sides of the equations}\\.\qquad-4x=8\qquad\text{divide both sides by (-4)}\\.\qquad x=-2\\\\\text{put the value of x to the second equation}\\\\8(-2)=84-20y\\-16=84-20y\qquad\text{subtract 84 from both sides}\\-100=-20y\qquad\text{divide both sides by (-20)}\\5=y\to y=5`