$(function () {
    function showOtherDonation() {
        $('.donate :input[name="donation"]').toggle();
        $('.donate :input[name="otherDonation"]')
            .focus()
            .parent().toggle();
        return false;
    }
    $('<p style="text-align: left; font-size: smaller"></p>')
        .append(
            $('<a href="#">other amount</a>')
            .click(showOtherDonation)
        )
        .insertAfter(
            $('.donate :input[name="otherDonation"]').parent()
        );
    $('.donate :input[name="donation"]').parent().show();
    $('.donate :input[name="otherDonation"]').parent().hide();
});