Using elimination to solve the system 2x + y = 8 and x + y = 4, which of the following could be the first step?
A. 2x + y = 8--------> 2x + y = 8
(x + y = 4)(-1)---> -x - y = -4
B. 2x + (4 - x) = 8
C. 2x + y = x + y
D. 3x + 2y = 12
E. x = 4
x—2 equations combined:
2x + y - x - y = 8 - 4
x = 4
y—1st equation, substitute x with 4:
2(4) + y = 8
8 + y = 8
y = 0
Answer: x = 4, y = 0
Proof—2nd equation:
4 + 0 = 4
4 = 4....