Choosing different widths for each widget area with Code Snippets

Hello!
I would like to change the widths of the footer widgets in this way, is my code correct?:

add_filter('generate_footer_widget_1_width','tu_custom_footer_1_width');
function tu_custom_footer_1_width(){
    // Return the percentage of this widget width - 10% in this case
    return'10';
}

add_filter('generate_footer_widget_2_width','tu_custom_footer_2_width');
function tu_custom_footer_2_width(){
    // Return the percentage of this widget width - 20% in this case
    return'20';
}

add_filter('generate_footer_widget_3_width','tu_custom_footer_3_width');
function tu_custom_footer_3_width(){
    // Return the percentage of this widget width - 20% in this case
    return'20';
}

add_filter('generate_footer_widget_4_width','tu_custom_footer_4_width');
function tu_custom_footer_4_width(){
    // Return the percentage of this widget width - 20% in this case
    return'20';
}

add_filter('generate_footer_widget_5_width','tu_custom_footer_5_width');
function tu_custom_footer_5_width(){
    // Return the percentage of this widget width - 30% in this case
    return'30';
}

I've never added php code I've installed code snippets to do it.

Could you tell me how?
Thank you!!