4x - 7y = 7
3x - 9y = 7
3(4x - 7y = 7)
12x - 21y = 21
-4(3x - 9y = 7)
-12x + 36y = -28
12x - 21y = 21
-12x + 36y = -28
15y = -7
y = -7/15
4x - 7(-7/15) = 7
4x + 49/15 = 7
4x = 7 - 49/15
4x = 105/15 - 49/15
4x = 56/15
x = (56/15) / (4)
x = (56/15) * (1/4)
x = 56/60 or 14/15
So the solution is x = 14/15 and y = -7/15 or (14/15, -7/15)
Verify solution by plugging in x and y values and solving.
