Your unit cost will be $0.11 :)
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Zero property because you are using zeros to multiply
All you do is add them all together...
20 + 11.4 + 11.4 + 4.5 + 4.5 + 0.45 + 0.45 + 0.45 + 0.45 = 53.6Kg
(note that 0.45 is 450g in Kg, When adding things such as weight or length you want to make sure that they are all in the same unit)