$1)$ Suppose demand for smart tablets is estimated to be

Q $=10005$p $+10$pa $2$pb $+0\mathrm{.}1$Y

where p is the price of tablets, pa and pb are the prices of related goods, A and B$,$ respectively. If

p $=80,$

pa $=50,$

pb $=150,$ and

Y $=$ $$20,000.$

a$.$ What is the price elasticity of demand? Explain your result if the price falls by $3\%$ and increases by $5\%.$ Also discuss possible impacts of a price change on revenues in two$-$three lines.