I need to create a formula that will estimate when an amount of funds will
run out based on current usage.

If:
TOTAL APRIL SPEND O91: =SUBTOTAL(9,O2:O89)
Purchase Order TOTAL O93: $1,791,260.00
TOTAL SPENT THROUGH 4/28/07 O94: =O91+'MARCH BILLINGS ''07'!O61
FUNDS REMAINING ON PO O95: =O93-O94

I need a formula that will calculate on what date O95=0 if monthly spend
continues at April amount. Please help!!! =)