How do I insert a ruby variable into a div

I want to use divs that resize based on the presence of certain ruby
variables.

How would I insert my size variable into a div like this

<% @width = 30 %>

<%=
"<div id='inner_meal_pan_overview' width='100%'
style=\"width:#{@width}em;\">"
%>

How would I insert my size variable into a div like this

<% @width = 30 %>

<%=
"<div id='inner_meal_pan_overview' width='100%'
style=\"width:#{@width}em;\">"
%>

that's not absolutely wrong, only those slashes are not necessary
if you use single parentheses:
<%= "<div id='inner_meal_pan_overview' width='100%'
style='width:#{@width}em;'>" %>

or:
<div id='inner_meal_pan_overview' width='100%' style='width:<%= @width
%>em;'>

Also <% @width = 30 %> should really go in the controller action