$oride='';
    $count = "25";
    $origin = $_POST["origin"];
    $destinataion = $_POST["destination"];
    $oride = ($destination = $_POST["destination"] - 
    $origin= $_POST["origin"]);
    if ($oride <="0"){
        echo "invalid";
    }
    elseif ($oride <="15"){
        echo $count;
    }
    elseif ($oride ="16"){
        echo $count + "1";
    }
    elseif ($oride ="17"){
        echo $count + "2";
    }
if statement is ok until $oride ="16" but when it reaches $oride ="17" it still choes 26 it should be 27
 
    