Step-by-step explanation:
Equation: [tex]4(3+x)=36[/tex]
First step:
[tex](4*3)+(4*x)=36[/tex]
Second step:
[tex]12+4x=36[/tex]
Third step:
[tex]4x=36-12\\4x=24[/tex]
Fourth step:
[tex]x=\frac{24}{4}\\ x=6[/tex]