Solution:-

From the figure,

XY || QR, PX = 1 cm, QX = 3 cm, YR = 4.5 cm and QR = 9 cm,

So, PX/QX = PY/YR

1/3 = PY/4.5

By cross multiplication we get,

(4.5 × 1)/3 = PY

PY = 45/30

PY = 1.5

Then, ∠X = ∠Q

∠Y = ∠R

So, ∆PXY ~ ∆PQR

Therefore, XY/QR = PX/PQ

XY/9 = 1/(1 + 3)

XY/9 = ¼

XY = 9/4

XY = 2.25