The answer is : The demand is elastic.
Elasticity =
[(80,000 - 180,000)/((80,000+180,000)/2)]/[($40 - $30)/(($40 + $30)/2)]|
[(-100,000/130,000)]/[(10/55)] = -.7692/.1818= -4.23
The answer is -4.23, however when considering own price elasticity of demand, we ignore the negative sign and look at the absolute value to determine whether it is elastic or inelastic.