Use the table below to answer question 17 and 18.
Market Demand Schedule for Commodity X. \(\begin{array}{c|c}
\text{ Price N} & \text{Quantity(Million units)} \\ 60 & 100 \\
50 & 140 \\
40 & 220 \\
30 & 260 \\
20 & 300 \\
10 & 340 \\
\end{array}\)
If the price of commodity X falls from N40.00 to N30.00 what is the price elasticity of demand?