21 students are 7th graders
Step by step explanation
Because 70 students is 100% and 30% of of the 100% which is 70 all you have to do is multiple my 0.3 since it’s 30 percent you do 0.3 which equals 0.30 if it was 3% you would use 0.03 that was just to let you know now if you multiple 70 times 0.3 you get 21 which is the number of students that are 7th graders.