On a math test, 60% of the students used a pencil. half of the remaining students used a red pen. if 6 students used a rend pen, how many students are in the class?

60% used a pencil..that leaves  40% remaining students (100% - 60% = 40%)
half of those used a red pen...so 20% used a red pen. (40% / 2 = 20%)
6 students used a red pen. so... 6 students is 20% of what number ?
6 = 0.20x
6/0.20 = x
30 = x
There are 30 students in the class