
Answer:
a. The average is  =(++) .
b. He can use the formula  =−− q sub 3 , equals 3 x minus , q sub 1 , minus , q sub 2. He will need a score of  =()−−= q sub 3 , equals 3 open 90 close minus 85 minus 88 equals 97 on his third quiz.
Step-by-step explanation: