Does anyone know the answer

B

Step-by-step 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