The quantity demanded of a commodity falls by 5 units when price rises by Rs 1 per unit. Its elasticity of demand is (-) 1.5 . Calculate the price before change if this price quantity demanded was 60 units.

$\u2206Q=-5\phantom{\rule{0ex}{0ex}}\u2206P=1\phantom{\rule{0ex}{0ex}}{E}_{d}=(-)1.5\phantom{\rule{0ex}{0ex}}{Q}_{0}=60\phantom{\rule{0ex}{0ex}}{P}_{0}=?\phantom{\rule{0ex}{0ex}}\phantom{\rule{0ex}{0ex}}{E}_{d}=\frac{\u2206Q}{\u2206P}\times \frac{{P}_{0}}{{Q}_{0}}\phantom{\rule{0ex}{0ex}}-1.5=\frac{-5}{1}\times \frac{{P}_{0}}{60}\phantom{\rule{0ex}{0ex}}{P}_{0}=Rs18$

Therefore, the price before change was Rs 18.

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