$(document).ready(function(){
    $(".box-manetl").css('margin-right', '20px');
    $(".box-manetl:last-child").css('margin-right', '0px');
    
    var box1 = 0;
    var box2 = 0;
    var box3 = 0;
    var line = 0;
    $('.box-1 .box-unten .box-block .frage').each(function(index)
    {
        box1 = $(this).height();
        box2 = $('.box-2 .box-unten .frage:eq('+ index +')').height();
        box3 = $('.box-3 .box-unten .frage:eq('+ index +')').height();
        
        if(box1 >= box2 && box1 >= box3)
            line = box1;
        else if(box2 >= box1 && box2 >= box3)
            line = box2;
        else
            line = box3;
        
     
        
        $(this).height(line);
        $('.box-2 .box-unten .frage:eq('+ index +')').height(line);
        $('.box-3 .box-unten .frage:eq('+ index +')').height(line);
    });   
});