Not quite the same equation as yours, sorry couldnt be bothered to follow instructions.
=(Sheet1!C11+Sheet2!C16*Sheet3!D1)-Sheet3!E6-Sheet2!E23
You can just hit = then go and click the cells you want to enter in your formula even if they are on different sheets.
Just for info you can even do it over different excel documents
=[Workbook1.xls]Sheet1!$A$5*[Workbook1.xls]Sheet2!$C$29-H25+Sheet2!D7