please help me explain what his mistake was. If possible does anyone think they can explain it in a simplified way? Thank You for your help!

Answer:
Dont think eh multiplied both sides by 4. That would be the first step.
Step-by-step explanation:
1/4(x+12)=2
multiply both sides by 4
x+12=8
move the 8 to the right side of the equation and change its sign
x=8-12
calculate
x= -4
Answer:
He didn't multiply 1/4 between both terms in the brackets.
Step-by-step explanation:
1/4(x+12)=2
1/4x+3=2
1/4x= -1
x= -4
Hope that makes sense!