Trend function in excel

Hello.

I am working on a spreadsheet to forecast billing for next financial year. My spreadsheet is set up as follows:

List of clients in column A (i.e. client on each row from 1 to 200) and financial years as column heads from B (2021) to F (2025)

In column F I an extrapolating data using the trend function from the data in columns B to E.

Where there has been a decline in sales for any particular customer, the trend function is returning a negative amount in column F.

How do I input this formula so that any row which would return a negative number instead returns "0"?

I think this should be done by embedding the trend formula inside an if formula, but i cannot seem to get that right. The box either reads as "false" or the problem with formula box pops up.