Question 785319
a)Let the function be Q(P)=aP+b, then 
*[invoke linear "a","b",163,1,175,153,1,214]
Q(P)=-3.9P+810.7
When P=156, Q(P)=202.3=202 millions

b)-3.9P+810.7-(-3.9*(P+1)+810.7)=3.9 millions=3900000
.....sales of cell phones decrease by 3900000.