show an element if a checkbox is unchecked

Question

I have an array of check boxes which are dynamically build from single checkbox.i.e,

<input type='checkbox' class='case' name='case' id='case$SlNo' value='$SlNo' checked='checked'/>.

Here the $SlNo is from 1 to number of rows created. So each check box have different id,

like case1,case2,...Along with this each check boxes there is a select drop down ,i.e

<select class='txtReason' name='txtReason$SlNo' id='txtReason$SlNo' hidden='hidden'></select>

it's id is also unique.It is hidden in default. I have to show that hidden element while unchecking

the checkbox by unique.I am doing this in PHP. My main problem is i cannot identify the check box which i am

unchecking. At the time of unchecking i have to show the corresponding hidden element through JQuery.

Please help me!!!