PLEASE HELP!
An airplane flying at an altitude of 18,000 feet has just begun its descent, and it will descend at a rate of 450 feet per minute.
Which of these equations represents the airplane's altitude, y, in feet after it has been descending for x minutes?
A. y equals negative 450 x minus 18,000
B. y equals negative 450 x plus 18,000
C. y equals 450 x minus 18,000
D. y equals 450 x plus 18,000
