Respuesta :

gmany

Answer:

[tex]\huge\boxed{a=-21}[/tex]

Step-by-step explanation:

[tex]-7=\dfrac{1}{3}a\to\dfrac{1}{3}a=-7\qquad|\text{multiply both sides by 3}\\\\3\!\!\!\!\diagup\cdot\dfrac{1}{3\!\!\!\!\diagup}a=(-7)(3)\\\\a=-21[/tex]