Answer:
[tex]x = 12[/tex]
Step-by-step explanation:
[tex]3x - 1 + x + 7 = 54[/tex]
[tex]4x + 6 = 54[/tex]
[tex]4x + 6 - 6 = 54 - 6[/tex]
[tex]4x = 48[/tex]
[tex] \frac{4x}{4} = \frac{48}{4} [/tex]
[tex]x = 12[/tex]
[tex]3(12) - 1 + (12) + 7 = 54[/tex]
[tex]36 - 1 + 12 + 7 = 54[/tex]
[tex]35 + 12 + 7 = 54[/tex]
[tex]35 + 19 = 54[/tex]
[tex]54 = 54[/tex]
