=
Multiply both sides by 12, so that we get rid of the fraction in x.
12 · (x+3)/12 = 2/7 · 12
Simplify.
x + 3 = 24/7
Then, subtract 3 from both sides, so that "x" gets isolated.
x = 24/7 - 3
Turn "3" into an improper fraction so that we could find the value of x easier.
3 = 21/3
So :
x = 24/7 - 21/7
Simplify.
x = 3/7
~Hope this helps!~