The owner first lost Rs. 100 in cash, but after the thief bought Rs. 60 goods, he get back that Rs. 100 but he lost Rs. 60 value of goods and Rs. 40 in change.
Compressions and Rarefactions are characteristic of Longitudinal waves.
The direction of vibration of the particles is in the same plane as in which the wave is propagating. The particles vibrate back and forth, about their mean positions.