5x-4y=30 -4x-2y=24
solve by substitution method
5x - 4y = 30
-4x - 2y = 24
-4x - 2y = 24
-2y = 4x + 24
y = (4x + 24) / -2
y = -2x - 12
5x - 4y = 30
5x - 4(-2x - 12) = 30
5x + 8x + 48 = 30
13x = 30 - 48
13x = -18
x = -18/13
-4x - 2y = 24
-4(-18/13) - 2y = 24
72/13 - 2y = 24
-2y = 24 - 72/13
-2y = 312/13 - 72/13
-2y = 240/13
y = (240/13) / -2
y = -120/13
Check...
5x - 4y = 30
5(-18/13) - 4(-120/13) = 30
-90/13 + 480/13 = 30
390/13 = 30
30 = 30
Correct answer: x = -18/13, y = -120/13