Answer:
$60
Explanation:
Data provided in the question
Alex willing to pay = $20
Kara willing to pay = $15
Susie willing to pay = $25
So, by considering the above information, the fifth unit of the public good that the government should produced is
= Alex willing to pay + Kara willing to pay + Susie willing to pay
= $20+ $15 + $25
= $60
Basically we added the willing to pay of these three persons that are displayed above