The correct way to solve this equation would be:
7=5+3(x-4)
Distribute the Brackets.
3*x=3x
3*4=12
7=5+3x-12
Add like terms.
7=-7+3x
Add 7 to both sides.
(7)+7=(-7+3x)+7
14=3x
Divide both sides by 3.
(14)/3=(3x)/3
4.6667 or 14/3 =x
Both answers are incorrect.
Some the significant mistakes:
-Didn't follow BEDMAS
-How did 7=8(x-4) turn into 78=x-4?
Hope this helps.
-Benjamin