Please answer this question:

Assume you start your career today and you are paid a full years salary of $71550 at the end of every year. assume your salary increases by 4% per year. If you earn an annual return of 7.69% from a vanguard balanced index fund admiral share, what percent of your annual salary do you have to save to reach retirement goal (starting work at age 28, planning to retire at age 67)

***PLEASE SHOW ALL STEPS OF CALCULATIONS, THANK YOU! :)