<?php

function myFilter($var){
    return ($var !== NULL && $var !== FALSE && $var !== "");
}

function calculate($exp) {
	$numbers = array_filter(preg_split('#[+-]|[*/=]#', $exp), "myFilter");
	$operations = array_filter(preg_split('#\\d#', $exp), "myFilter");
	
	$result = $numbers[0];
	$counter = 1;

	foreach ($operations as $operation) {
    	if ($operation == "+") $result += $numbers[$counter];
		if ($operation == "-") $result -= $numbers[$counter];
		if ($operation == "*") $result *= $numbers[$counter];
		if ($operation == "/") $result /= $numbers[$counter];
		if ($operation == "=") return $result;

    	$counter++;
  }
	
}

$res = floor(calculate("95+89+11+2-48/9*73-700/2="));

echo $res;