What is the weighted average?

Suppose you have a class where you have four quizzes each worth 15% of the grade and two exams each worth 20%. If you make 77% on two quizzes, 100% on one, and 86% on the fourth along with 98% on one exam and 66% on the other. What is the weighted average?

Please see the attachment for additional insight into what I am looking for in this DQ. Remember that the work needs to be completed in Excel along with the proper Excel formulas.

NOTE: The weighted average must use the 15% and the 20% and is NOT an average of the quizzes and exams.