A. The expression given in the question is
c = 6x + (900000/x)
c = (6x^ +900000)/x
I hope that this is the expression that you were looking for.
b. When x = 240, then
c = [6 * (240)^2 + 900000]/ 240
= (6 * 57600) + 900000/240
= (345600 + 900000)/240
= 5190
From the above deduction, it can be concluded that the cost of ordering and storing is 5190. I hope the procedure is clear enough for you to understand.
She practiced 630 hours in all because you multiply 18x35
(4h+2)(2h+8)
4htines 2h= 8h^2
4htimes8=32h
2 times 2h=4h
2 times 8=16
Add Middle two you have
8h^2+36h+16
30. is just asking where the two equations graphed intersect each other...
x = -3 and x = 1 for intersections.
I = PRT
$360 = $8000 x R X 1
$360 = $8000 X R
$360/$8000 X R /$8000
0.045 = R
R= 0.045 * 100
R = 4.5%