Answer:
11
Step-by-step explanation:
You have to balance it out. Since Ella has 9 acorns in one hand and 10 in the other and 9+10=19, she has 19 acorns in total. So you have to figure what number would give Frank 19 acorns as well. You can do this by subtracting 8 (the amount he has in one hand) from 19 (the total number of acorns he has). Since 19-8=11, he has 11 acorns in his other hand.
