A box of cereal contains 725 grams of cereal. To make a bowl of cereal.r, grams of cereal is removed from the box What equation models the relationship between the quantity of cereal removed, r, and the quantity of the cereal in the box, b?
A: b = 725 - r
B: b = 725r
C: r= 725b
D: r = 725-b
