Idon't understand and how do i do it

Ok so she has 3 small containers holding 8 pounds of birds seeds and 6 large containers of bird seed that each hold 12 pounds of bird seed, and she has already used 4 pounds so lets find how many pounds of bird seed she has altogether 8*3=24 6*12=72 and adding the leftover 24+72-4=92 now she wants to fill 30 bird feeders needing 2 pounds each, would require 60 pounds of bird seed now that she used 60 more pounds of seed 92-60=32 she would have 32 pounds of bird seed leftover now an equation to use to solve this is (3(8))+(6(12))-4-(30(2))=the amount of bird seed left over hopefully this gave you an idea on how to do this the way you are supposed to