Find the ordered pair $(x,y)$ that satisfies the system of equations\begin{align*} x+3y &= -4,\\ 3x -7y &= 36. \end{align*}
Someone please help me.
x + 3y = -4 ⇒ x = -4 - 3y (1)
3x - 7y = 36 (2)
Sub (1) into (2)
3 ( -4 -3y) - 7y = 36
-12 - 9y - 7y = 36
-9y -7y = 36 + 12
-16y = 48
y = 48 / -16 = -3
And x = -4 - 3(-3) = -4 + 9 = 5
