Respuesta :
Answer:
A) -3
Step-by-step explanation:
-3x+7x=-12(add -3 and +7 which gives +4 or just 4)
so 4x=-12(divide 4 on both sides of equation)
that gives x=-3 as 4/4 is one and 12/4 =3 and because there is minus sign in front of 12 so it is -3