Answer:
B
Explanation:
3x + 7y = - 49 → (1)
10x - 7y = - 42 → (2)
adding (1) and (2) term by term will eliminate y
13x + 0 = - 91
13x = - 91 ( divide both sides by 13 )
x = - 7
substitute x = - 7 into either of the 2 equations and solve for y
substituting into (1)
3(- 7) + 7y = - 49
- 21 + 7y = - 49 ( add 21 to both sides )
7y = - 28 ( divide both sides by 7 )
y = - 4
solution is (- 7, - 4 ) → B