在php中将for循环的变量返回值加起来

I have this code that is working perfectly. My question is how can I sum all the value of $manpowerCost and $otherCharges?

for ($i = 1; $i<=9; $i++) {
$m = '0'.$i;
$sumMc = array();
$revenue = revenue($project, $year.'-'.$m);
$manpowerCost = manpowerCost($project, $year.'-'.$m);
$otherCharges = otherCharges($project, $year.'-'.$m);
$netIncome = netIncome($revenue, $manpowerCost, $otherCharges);

if ($manpowerCost<=0 && $m <= $projected_date){
    $manpowerCost = round(($projected_mc * $percentage_mc),2);
    $projected_total_mc += $manpowerCost;
    $pt = $pt + $manpowerCost;
} else {
    $projected_mc = $manpowerCost;
    $manpowerCost = $projected_mc;
}

if ($otherCharges<=0 && $m <= $projected_date){
    $otherCharges = round(($projected_oc * $percentage_oc),2);
    $projected_total_oc += $otherCharges;
    $pt = $pt + $otherCharges;
} else {
    $projected_oc = $otherCharges;
    $otherCharges = $projected_oc;
}
echo    '<td>RE:'.number_format($revenue, 2, '.', '').'<br />MC:'.number_format($manpowerCost, 2, '.', '').'<br />OC:'.number_format($otherCharges, 2, '.', '').'<br />NI:'.$netIncome.'</td>';
}

U can Try like this

$powercost_total = '0';
for ($i = 1; $i<=9; $i++) {
$manpowerCost = manpowerCost($project, $year.'-'.$m);
$powercost_total = $manpowerCost + 4powercost_total;
....

Declare $TotalManPowerCost and $TotalOtherCharges variables outside of the loop, and add $manpowercost and $otherCharges to them in each iteration of the loop