Well if you prefer maintaining a c&p job over 4 LOC… ^^
anyway to answer your other question, try
$('#btnbag1a').click(function(event) {
event.preventDefault()
$('#bag1a').toggle()
})
On another note, you might actually link to the elements in questions, like
<a id="btnbag1a" class="light-blue btn" href="#bag1a">Show/Hide Parts</a>
The JS might thus become
$('#btnbag1a').click(function(event) {
event.preventDefault()
$('#' + this.href).toggle()
})
… and with the following CSS…
#bag1a:target {
display: block;
}
… it will still get you to (and show) the corresponding element if JS is disabled. (This one was for @felgall…)