TeX source:

\begin{aligned} \% \text { change in quantity } &=\frac{3,000-2,800}{(3,000+2,800) / 2} \times 100 \\ &=\frac{200}{2,900} \times 100 \\ &=6.9 \\ \% \text { change in price } &=\frac{60-70}{(60+70) / 2} \times 100 \\ &=\frac{-10}{65} \times 100 \\ &=-15.4 \\ \text { Price Elasticity of Demand } &=\frac{6.9 \%}{-15.4 \%} \\ &=0.45 \end{aligned}