Calculate comm based on full collection within 60days

Hi,

i need some guidance on the following:-

1) Calculate the commission based on the target sales & following by collection.
mean sales target achieve then the team entitle to get the commission based the table in % if not no comm given
2) If achieve the sales target , then the commission will base on the collection but within 60days due .

Can someone show me the formula to calculate the commission rate.

attach is the data for your advise and reply....