Jackson's scores on the first four algebra quizzes are 76, 87, 92, and 71. What score must he earn on the fifth quiz to earn an average quiz score of 85? Please set up and solve this problem following the steps below:
a) Define the unknown quantity in terms of one variable.
b) Translate the question into an equation.
c) Solve the equation, showing all work.
d) Write a complete answer to the question asked.