On a certain exam, Tony corrected 10 papers and found

the mean for his group to be 70. Alice corrected the remaining
20 papers and found that the mean for her
group was 80. What is the mean of the combined group
of 30 students?

2 answers

10 * 70 = 700
20 * 80 = 1600

700 + 1600 = 2300
2300 / 30 = ?
76.6