Answer:
<em>She will take 10 weeks to save the money for the DVD player</em>
Step-by-step explanation:
Let w = Lianne's weekly allowance.
The DVD player costs 2 1/2 times her weekly allowance, thus
DVD cost = 5/2w
She gets w every week but spends 3/4w on other things, thus the remaining money is
Weekly savings =w - 3/4w = 1/4w
To know the number of weeks needed, we divide the DVD cost by the weekly savings:

Operating:

N = 10
She will take 10 weeks to save the money for the DVD player
Answer:
--
x = 2.3
Step-by-step explanation:
3 x + 5 = 17
- 5 = -5
------------------------
3x 7
----- = -----
3 3
-------------------------
---
x = 2. 3
Answer:

Step-by-step explanation:
Let r be the radius of the semicircle, then 2r is the width of the rectangle. Let y be the length of the rectangle. The perimeter of the window consists of two lengths, one width and length of semicircle, then

Express y:

The area of the window is

Substitute y into the area expression:

Find the derivative A':

Equate A' to 0:

When
then
and the function A is increasing, when
then
and the function A is decreasing. This means that at point
the function A takes it maximal value (the area is maximal).
Step-by-step explanation:

It's a horizontal line y = -9.
Look at the picture.
Answer: B.