[tex]\qquad\qquad\huge\underline{{\sf Answer}}[/tex]
Let's solve for x ~
[tex]\qquad \tt \dashrightarrow \: 4(3 + x) + x = x + 4[/tex]
[tex]\qquad \tt \dashrightarrow \: 12 + 4x+ x = x + 4[/tex]
[tex]\qquad \tt \dashrightarrow \: 5x + 12 = x + 4[/tex]
[tex]\qquad \tt \dashrightarrow \: 5x - x = 4 - 12[/tex]
[tex]\qquad \tt \dashrightarrow \: 4x = - 8[/tex]
[tex]\qquad \tt \dashrightarrow \: x = - 8 \div 4[/tex]
[tex]\qquad \dashrightarrow \: \boxed{ \tt x = - 2 }[/tex]
