There are 70 students in the school band. 40% of them are sixth graders, 20% are seventh graders, and the rest are eighth graders. How many sixth graders, how many seventh graders and how many eighth graders?

Answer:Sixth graders: 14Seventh graders: 28Eighth graders: 28Step-by-step explanation:To solve this you just have to use a rule of three to solve the percentages, remember that the 100% will be the 70 students, and we solve each case separetly:70 students= 100%sixth grades=   40%Sixth grades= (40*70)/100Sixth graders= 2870 students= 100%seventh grades=   20%seventh graders=   (20*70)/100Seventh graders=14So if we have that the rest of the students are eighth graders, we just add up the sixth and seventh graders and withdraw them from the total:28+14=4270-42=28SOwe have that the eighth graders are 28