Respuesta :

crystivia

Answer:

-3

Step-by-step explanation:

Let x equal the mystery number

Our equation will be:

x - 5 = 1 + 3x

Subtract x from both sides

-5 = 1 + 2x

Subtract 1 from both sides

-6  = 2x

Divide both sides by 2

-3 = x