The math club has 57 members who are in sixth or seventh grades there are twice as many sixth graders as seventh graders how many sixth graders are in the club

X = 6th graders
y = 7th graders

x + y = 57
x = 2y

2y + y = 57
3y = 57
y = 57/3
y = 19 <=== there are 19 seventh graders

x = 2y
x = 2(19)
x = 38 < there are 38 sixth graders

She will need 5/8 bags for each square yard.