3 weeks(last, current, next) use date

$dateNow = "04/28/2016";
$timestamp = strtotime($dateNow);
$currDayOfWeek = date("w", $timestamp);

$startDayOflastWeekT = strtotime(-($currDayOfWeek + 7) . " days", $timestamp);
$startDayOflastWeek = date("m/d/Y", $startDayOflastWeekT);
$endDayOflastWeekT = strtotime("+ 6 days", $startDayOflastWeekT);
$endDayOflastWeek = date("m/d/Y", $endDayOflastWeekT);

$startDayOfMiddleWeekT = strtotime("+ 7 days", $startDayOflastWeekT);
$startDayOfMiddleWeek = date("m/d/Y", $startDayOfMiddleWeekT);
$endDayOfMiddleWeekT = strtotime("+ 13 days", $startDayOflastWeekT);
$endDayOfMiddleWeek = date("m/d/Y", $endDayOfMiddleWeekT);

$startDayOfNextWeekT = strtotime("+ 14 days", $startDayOflastWeekT);
$startDayOfNextWeek = date("m/d/Y", $startDayOfNextWeekT);
$endlastDayOfNextWeekT = strtotime("+ 21 days", $startDayOflastWeekT);
$endlastDayOfNextWeek = date("m/d/Y", $endlastDayOfNextWeekT);


echo $startDayOflastWeek . " - " . $endDayOflastWeek . "\r\n";
echo $startDayOfMiddleWeek . " - " . $endDayOfMiddleWeek . "\r\n";
echo $startDayOfNextWeek . " - " . $endlastDayOfNextWeek . "\r\n";