B
given the 2 equations
2x + y = 1 → (1)
9x + 3y = - 3 → (2)
from (1) : y = 1 - 2x
substitute y = 1 - 2x in (2)
9x + 3(1 - 2x) = - 3 ( distribute and simplify left side )
9x + 3 - 6x = - 3
3x + 3 = - 3 ( subtract 3 from both sides )
3x = - 6 ( divide both sides by 3 )
x = - 2 → B
