How to create a forecast

Hi,

Sorry I'm a bit stuck and hope someone would be able to help me. My manager would like to be able to predict how many job positions the team can hire based on the average days below. Each colour represents the average days of one recruitment stage to another. The other table shows how many candidates we got the average from. For example if the team was given 7 days to process candidates, how many would they be able to hire? And how many candidates would be in each stage?