Last year, there were 80 students in the orchestra. this year there are 100 students in the orchestra. determine the percent of increase in the number of students taking orchestra from last year to this year. a 25%, because 100-80/80= 25% b 20%, because 100-80/100= 20% c 80%, because 80/100= 80% d 125%, because 100/80= 125%