Adrien has 4 liters of milk. he drinks y liters each day. if adrien has x liters of milk left after one week, express d in terms of y.

The correct question is
Adrien has 4 liters of milk. He drinks y liters each day. If Adrien has x liters of milk left after one week, express x in terms of y

we know that
y> liters of milk that Adrien drinks each day
x> liters of milk left after one week
in one week
Adrien drinks 7y
and
x=4-7y

 the answer is 
x=4-7y