Answer: 25 sixth graders
Explanation:
Sixth-graders are in a ratio with fifth graders in the band at 5:4 and there are 20 fifth-grade students in the band.
To find the number of 6th graders, use direct proportion and assume the sixth grader number is x:
5 : 4
x : 20
4x = 100
x = 100 / 4
x = 25 sixth graders