how many different ways could 3 girls and 3 boys form a line if the line must alternate boys and girls

+ is a girl and = is a boy.

So let's say the line starts with a boy and ends with a girl, there's one way.

= + = + = +

Now, let's reverse it, to where it starts with a girl and ends with a boy.

+ = + = + = +

There are two ways to arrange the line if there must be alternating girls and boys

There are 2 ways if they must alternate boys and girls.