Determining the Number of Boys in Class

There are 30 students in Ms. Johnson's class. If the number of boys is represented as b and the number of girls as g, the following equation can be constructed:

$b + g = 30$

Furthermore, we know that there are 12 more girls than boys in the class. This gives us a second equation:

$g = b + 12$

How many boys are there in Ms. Johnson's class?