Answer:
(-4,15)
Step-by-step explanation:
Personally I think this works better with substitution, but I'll do it your way.
3x + y = 3
2x + y = 7 Subtract these two equations
x = - 4 3 - 7 = - 4
3x + y = 3 Substitute - 4 for x
3(-4) + y = 3 Combine
-12 + y = 3 Add 12 to both sides
-12 + 12 + y = 3+12
y = 15
Check
2x + y = 7
2*-4 + 15 = 7
- 8 + 15 = 7
7 = 7
It checks.
