Question 154181
2x+3y=21       eqn 1
-3x-6y=-24     eqn 2
----------
 4x+6y=42      eqn 1 doubled
Add
x + 0y = 18
x = 18
Sub for x in eqn 1
2*18 + 3y = 21
36 + 3y = 21
3y = -15
y = -5