First multiply the first row by 3:
-21x + 3y = -57
-2x + 3y + -19
Subtract those:
-19x = -38
Solve for x:
-19x = -38
/-19
x = 2
Then substitute x = 2 into either one.
-21(2) + 3y = -57
Solve for y:
-42 + 3y = -57
Regroup:
3y - 42 = -57
+42
3y = -15
/3
y = -5
