Here,
PQ∥XY and PQ=XY
PR∥XZ and PR=XZ
Taking ΔPQR and ΔXYZ,
PQ=XY
PR=XZ
∠QPX=∠YXM=a
∠RPX=∠ZXM=b
∠XYZ=∠YXM+∠ZXM=a+b
∠XYZ=∠QPR=a+b
⇒ΔPQR≅ΔXYZ