Drew has 50 red, green, and blue marbles. He has six more red marbles than blue marbles and four fewer green marbles than blue marbles. Write and solve an equation to determine how many blue marbles Drew has.
There are 50 red marbles but then drew added six more so its 56. Then she has 50 green marbles but took away 4 so now she has 46. And she left the blue marbles alone so its still 50.
