To find BC: Since XY is the bisector of AB and AC, this means that it is a median of triangle ABC. Its length will be half of the length of BC; 6 = 1/2BC; 6*2 = BC; 12 = BC
To find XZ: Since XZ is the bisector of AB and BC, this means that it is a median of triangle ABC. Its length will be half of the length of AC; 1/2(16) = 8.
To find BZX:
XYCZ is a parallelogram. Consecutive angles of a parallelogram are supplementary; 180-55=125=XZC.
XZC and BZX form a linear pair and are thus supplementary. This means that BZX = 180-XZC = 180-125 = 55
