It should be 8 if it is 5-5 which gives you 0.
Or it could be (5x5)-5=20+8=28.

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Answer:
20
Step-by-step explanation:
f(n)=n^2-n
f(-4)=(-4)^2-(-4)
f(-4)=16+4
f(-4)=20
Kilogram is an SI unit for mass.
Ounce and pound refer to American system for measuring things, and decakilogram is not the "basic" unit, but kilogram is.