Question 393643
Solve both equations for y:
x+3y-3=0
x+3y = 3
3y = -x + 3
y = (-1/3)x + 1
.
and 
2x-7y+20=0
2x-7y= -20
-7y= -2x - 20
y= (2/7)x + 20/7
.
set them equal to each other:
(-1/3)x + 1 = (2/7)x + 20/7
multiply both sides by 21:
-7x + 21 = 6x + 60
21 = 13x + 60
-39 = 13x
-3 = x
.
to find y plug into:
y = (-1/3)x + 1
y = (-1/3)(-3) + 1
y = (1) + 1
y = 2
.
intersection is at: (-3, 2)