$result = ( $a >= $b ) && ( $c < $d );
&& is a logical and so if 10 >= 3 and 7 < 20 then result is true
$result = ( $a < $b ) || ( $c <= $d );
|| is logical or so if 10 < 3 or 7 <= 20 then result is true
$result = $a % $b;
% is the modulo operator so result =10 mod 3