Respuesta :

Exvited
[tex] \frac{40-x}{3} = 4 + x \\ \\ 40 - x = 12 + 3x \\ \\ 40 = 12 + 3x + x \\ \\ 40 = 12 + 4x \\ \\ 40 - 12 = 4x \\ \\ 28 = 4x \\ \\ \frac{28}{4} = x \\ \\ 7 = x \\ \\ x = 7 \\ \\ Answer: \fbox {x = 7} [/tex]
TSO
[tex] \frac{40-x}{3} = 4 + x\\\\40 - x = 3(4 + x)\\\\40 - x = 12 + 3x\\\\40 = 12 + 4x\\\\4x = 28\\\\\boxed{\bf{x=7}}[/tex]