<div class="container">

    <div class="content">content</div>

    <div class="left">left</div>

    <div class="right">right</div>

</div>

.container{

		padding-left: 200px;

		padding-right: 150px;

}

.content {

	background: pink;

	width: 100%;

	float: left;

}

.left{

	width:200px;

	background: blue;

	float: left;

	margin-left: -100%;

	position: relative;

	right: 200px;

}

.right{

	width: 150px;

	background: green;

	float: left;

	margin-right: -150px;

}