Since A is the midpoint of BC, we can assume BA and AC are equal to each other.
We also know that BC = BA + AC = 23 + 23 = 46
The answer to this question is H. I hoped I helped you.
21+(5f)=61
Subtract 21 to both sides of the equation
5f=40
Divide both sides by 5
f=8
The answer is 8
