One half the members of the junior high math team are ninth graders. One fourth of the remaining members are eighth graders. One fifth of the rest are seventh graders. There are twelve 6th graders on the team. How many members on the team?

Answer 1

x/2 = 9th graders, leaving x/2
x/2 * 1/4 = x/8 = 8th graders, leaving x/2*3/4 = 3x/8
1/5 * 3x/8 = 7th graders, leaving 4/5*3x/8=3x/10
3x/10=12 = 6th graders.

So, the team has 40 members.
20 9th graders
5 8th graders
3 7th graders
12 6th graders