Answer: Cross price elasticity is - 0.12
Explanation:
Cross price elasticity measures the responsiveness of quantity demanded of good a to a change in any of its related variable such as good b.
[tex]Qa=86-5Pa-4Pb+2M[/tex]
Given,
Pa=6, Pb=3, and M=30,
[tex]Qa = 86 - 5(6) - 4(3) + 2(30)[/tex]
[tex]Qa = 86 - 30 - 12 + 60[/tex]
[tex]Qa=104[/tex]
So, cross price elasticity is given by
[tex]e_{pb} = \frac{Change in Qa}{Change in Pb} * \frac{Pb}{Qa}[/tex]
[tex]e_{pb} = -4 * \frac{3}{104}[/tex]
[tex]e_{pb} = -0.1153[/tex]
Since, cross price elasticity is negative it means that good a and good b are complements to each other.