pretty simple stuff
ok, so I will use coordinate style to explain
(row,collumn)
so a number in the place where 8th grade and twitter intersect, I put (8,T)
for total, I have A as the total
ok
the total of all the groups (bottom right corner) coordinate:(A,A) is 635
75 seventh grades said use instagram (put 75 in (7,I)
total of 321 facebook (bottom row, under facebook put 321)
of the 247 eighth grades (8th grade total is 247), 23 updated instagram most (put 23 in (8,I))
121 total 6th graders
158 twitter users total
45=6th grade twitter
123 8th grades using facebook
now we fill out what we are given (see 1st attachment)
we can see that
321+instagramtotal+158=635
solving, we get
instagramtotal=156
fill that in
we can now find the 6th grader instagrammers
6thinsta+75+23=156
6thinsta=58
fill that in
we can fill out 6th grader facebook
6thface+58+45=181
6thface=78
fill that in
now we can find how many 7th grades user facebook
78+7thface+123=321
7thface=120
fill that in
we can fid total 7th graders
181+7thtotal+247=635
7thtotal=207
fill that in
we find 7th twitter
120+75+7thtwitter=207
7thtwitter=12
fill that in
8th twitter
123+23+8thtwitter=247
8thtwitter=101
see completed table in 2nd attachment
