Youre answer is 3/10 or 36 were 6th graders. In order to get your answer first you need to add the two fractions. 3/5+1/6 ofc you need to make the bottom the same number so you convert them to 18/30 and 5/30 which equals 23/30 you simplify it and you should get 7/10. Now, if 7/10 of the students are 7and 8th graders, that means 3/10 of them are 6th graders. Then you figure out what is 1/10 of 120 which is 12 ans mulitiply by 3 which is 36