Answer
6%
8%
Work Step by Step
$E_d=\frac{\Delta\ qty}{\Delta\ price}$
Substitute the given values for traffic elasticity.
$0.3=\frac{\Delta\ qty}{20}$
$0.3\times20=\frac{\Delta\ qty}{20}\times20$
$6=\Delta\ qty$
$E_d=\frac{\Delta\ qty}{\Delta\ price}$
Substitute the given values for elasticity of fuel efficiency.
$0.4=\frac{\Delta\ qty}{20}$
$0.4\times20=\frac{\Delta\ qty}{20}\times20$
$8=\Delta\ qty$
