$mktime = explode("-",$rs_loan['datestart']);
 
$x = 5;
 
//to add $x to day
$newdate = date("Y-m-d",mktime(0,0,0,$mktime[1],$mktime[2]+$x,$mktime[0]));
 
//to add $x to month
$newdate = date("Y-m-d",mktime(0,0,0,$mktime[1]+$x,$mktime[2],$mktime[0]));
 
//to add $x to year
$newdate = date("Y-m-d",mktime(0,0,0,$mktime[1],$mktime[2],$mktime[0]+$x));