Apportioning Data over months

HI,

I am new to PowerBI, and am in need of some help

I have loaded invoice data which hold from and end dates as well as the invocie cost, I now need to setup a report so that the invoice periods are taken into account and the cost is apportioned monthly (there will be instances where invoice cover part periods and so the output should be able to handle this, buyt working out the daily average cost and then appliying to the the relevent months

Thanks Anthony