formula

I am in the consulting business and I bill my cleints at the beginning of each month based upon the work my employees and I have billed during the previous month--typically calculated at quarter hour increments. Within the billing statement I have a cell that reads:(12.5 hours @$50 per hour). I would like to have the number of hours--in this case 12.5-- pulled from another worksheet that totals up hours from a number of employees working for that particular client. How can I do this? Thank you.