Answer:
Mom decided to split the prize between my brother and (I).
Explanation:
As there is only two entities (in this case, two people, you and your brother), between would make the most sense. Among can be used in such a state, but it is generally used when there is either more than 2 persons or more than 2 groups of people.
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Answer:
it would be Brother and I
Explanation:
for say u wouldnt me like my brother and me like tacos. lets say your 59 you'd typically say, my brother and I like tacos