Question 402681
Please, look at how does your problem write down in the book:
in the first way {{{(12+x)/-4=(5x-7)/3+2}}} 
or in the second way {{{12+x/-4=5x-7/3+2}}}
.
The first
{{{(12+x)/-4=(5x-7)/3+2}}} 
{{{-(3*(12+x)/12)=(4*(5x-7))/12+(2*12)/12}}} Multiply all equation at 12
{{{-3*12-3*x=4*5x-4*7+24}}}
{{{-3x-20x=-28+24+36}}}
{{{-23x=32}}}
{{{x=32/(-23)}}}
{{{x=-32/23}}}
x=-1  9/23
.
The second
{{{12+x/-4=5x-7/3+2}}}
{{{-x/4-5x=-7/3+2-12}}}
{{{-x/4-(4*5x)/4=-7/3-10}}}
{{{(-x-20x)/4=-7/3-(3*10)/3}}}
{{{(-21x)/4=(-7-30)/3}}}
{{{-(21x)/4=-37/3}}}
{{{x=(37/3)*(4/21)}}}
{{{x=148/63}}}
x=2  22/63