Answer :
It is saying that if Mr Newberry had 7 marbles, 3 would be red and 4 would be blue. Basically, the question is asking you to do this:
Red: 28/3 =
Blue: 28/4 =
Red: 28/3 =
Blue: 28/4 =
3+4=7
28 divided by 7 equals 4.
3*4=12
4*4=16
12 marbles are red.
16 marbles are blue.
Check: 12+16=28
28 divided by 7 equals 4.
3*4=12
4*4=16
12 marbles are red.
16 marbles are blue.
Check: 12+16=28