Weight is in Olivia's backpack is 5/6 pound.
As in the given problem olivia's history book weights 1/2 of a pound and
her lunch weighs 2/3 of a pound.
As both the units are same,
Thus total weight must be summation of both history book and her lunch box.
total weight is =1/2 +2/3 pound
= (3+2)/6
that is equal to 5/6 pound.
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