PHP - ช่วยดูให้หน่อยครับเรื่อง if ง่ายๆ แต่ผมทำไม่เป็น

$A = 17;
$B = 4;

if($A == 20 && ($B > 3 && $B<=5)) {
echo "SUCCES";
} else {
echo "ERROR!";
}

$A = 17;
$B = 4;

if($A == 20)
{
            if($B > 3 && $B<=5 ) 
           {
               echo "SUCCES";
           }
} 
else
{
            echo "ERROR!";
}

<?php
$A = 20;
$B = 4;
$D = 18;



if($A == 20 && ($B > 3 && $B <=5)) {
$A = $NewA;
$B = $NewB;
echo $NewA;
echo $NewB;
}

if($D == 20 && ($B> 3 && $B <=5)) {
$A = $NewA;
$B = $NewB;
echo $NewA;
echo $NewB;
}
?>

<?php
$A = 20;
$B = 4;
$D = 18;

if($A == 20 && ($B > 3 && $B <=5)) 
{
	$NewA = $A;
	$NewB = $B;
	echo "Do A<br>";
	echo "NewA = $NewA<br>";
	echo "NewB = $NewB<br>";
	echo "-------------------------<br>";
}
else
{
	echo "Do A<br>";
	echo "A > 20 or < 20<br>";
	echo "-------------------------<br>";
}

if($D == 20 && ($B> 3 && $B <=5)) 
{
	$NewA = $A;
	$NewB = $B;
	echo "Do D <br>";
	echo "NewA = $NewA<br>";
	echo "NewB = $NewB<br>";
	echo "-------------------------<br>";
}
else
{
	echo "Do D<br>";
	echo "D > 20 or < 20<br>";
	echo "-------------------------<br>";
}
?>