Inactive Tutor answered 03/24/22
two equations, two unknowns can be solved by substitution and elimination or matrix algebra
it also sometimes helps to graph the two equations and see where they intersect
y = (1/3)x -1
3y = x-3
x = 3y+3
5x=9y
5(3y+3) = 9y
15y +15 = 9y
6y = -15
y =-15/6 = -5/2 = -2.5
x =3y+3 = 3(-5/2)+3 = -15/2 +3 = -9/2 = -4.5
graphically, the point of intersection of the two lines is (-4.5, -2.5)
check the answer by plugging that point into each equation, x= -4.5, y =-2.5
y= (1/3)x -1
-2.5 = (1/3)(-4.5) -1 = -1.5 -1 -2.5
5x = 9y
5(-4.5) = 9(-2.5)
-22.5 = -22.5