Answer:
u just write it down on a paper
Step-by-step explanation:
it is obvious no offense
A door,picture frame,desktop,books
9 x 1 = 9
9 x 2 = 18
9 x 3 = 27
9 x 4 = 36
9 x 5 = 45
9 x 6 = 54
9 x 7 = 64
9 x 8 = 72
9 x 9 = 81
9 x 10 = 90
Answer:
600
Step-by-step explanation:

x max = 
a = -5
b = 6
-6/2(-5) = 6/10 = 3/5 = .6
.6 thousand = 600
600 speakers should be sold.
Alternatively, you can check the vertex of the parabola formed.