Which of the following pair of equations could NOT be considered a system of
linear equation in two variables?
A. {
7 − = 8
2 + 4 = 8
C. {
− + 6 = 2
7 = − 12
B. {
= − 8
5
2
+ 4 = 8
D. {
4
2 − 3 − 4 = 0

2 = −9