Every student in the school math club is either in 7thth or 8th grade, and either has blue, green, or brown eyes. There are 46 students in the math club. Of these students, 9 students are 7th graders with blue eyes, 9 students are 8th graders with brown eyes, and a total of 9 students have green eyes. There are three times as many th graders as there are students with blue eyes, and twice as many students with brown eyes as there are 8th graders. How many students in the math club are 7th graders with green eyes?