how to find two date under how many mondays find in php

1<?php
2    $startDate = "01-10-2020"; 
3    $endDate = "31-10-2020"; 
4    $resultDays = array('Monday' => 0, 
5    'Tuesday' => 0, 
6    'Wednesday' => 0, 
7    'Thursday' => 0, 
8    'Friday' => 0, 
9    'Saturday' => 0, 
10    'Sunday' => 0); 
11  
12    // change string to date time object 
13    $startDate = new DateTime($startDate); 
14    $endDate = new DateTime($endDate); 
15  
16    // iterate over start to end date 
17    while($startDate <= $endDate ){ 
18        // find the timestamp value of start date 
19        $timestamp = strtotime($startDate->format('d-m-Y')); 
20        // find out the day for timestamp and increase particular day 
21        $weekDay = date('l', $timestamp); 
22        $resultDays[$weekDay] = $resultDays[$weekDay] + 1; 
23        // increase startDate by 1 
24        $startDate->modify('+1 day'); 
25    } 
26    // print the result 
27    print_r($resultDays); 
28    $totaldays = 0;
29    foreach ($resultDays as $key => $value)
30    {
31        if($key == "Monday")
32            $totaldays += $value;
33        if($key == "Friday")
34            $totaldays += $value;     
35    }
36    echo $totaldays;
37?>
38  //@sujay