Business & farm

I have 5 investments that issue a K-1 and one of them has excess business interest being reported.  I have from 8990 and I have looked at the IRS’s instructions on this form but found it totally useless explaining how to do the calculations.  I simply have investments that spin out capital gains, dividends, margin interest, wages from a part time job and some social security and these damned K-1s.

 

Do you or anyone else have a link to any examples how to do form 8990 or clearer explanation what is needed to come up with the numbers on 8990?