Answer: B) 6
Step-by-step explanation:
Segment BA is half as long as ZY, since BA is a midsegment.
This means ZY is twice as long as BA
ZY = 2*BA
2*BA = ZY
2*(x-1) = 10
2x-2 = 10
2x = 10+2
2x = 12
x = 12/2
x = 6
Note how this leads to BA = x-1 = 6-1 = 5, which is half as long as ZY = 10.