he should use 3.5 cups of milk.
bc three goes into seven 2 1/3 times.
and 1/3 of 1.5 is 0.5
since 3 goes into 7, 2 times, he uses 3 cups of milk, and sinze 1/3 of 1.5 is 0.5, add them together and you get 3.5
i hope that made sense
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