so which is equivilentpemdas
(8-6x+12)(20-6x)multiply/distribute1/4(20-6x)5-6/4x=5-3/2x=-3/2x+5
the answer is D
so mean is equivilent to average
per minute means x feet for every one minute=xfeet/1miin=x/1
so just divide -378/7=-54
mean change in altitude-54 feet per minute