<h3>
<u>Answer:</u></h3>

<h3>
<u>Step-by-step explanation:</u></h3>
Given function to us is :-
And we , need to write the function a a product of linear factor by grouping or using the x method or a combination of both . So let's factorise this ,
I have also attached the graph of x²-9.
<h3>
<u>Hence </u><u>option</u><u> </u><u>A</u><u> </u><u>is</u><u> </u><u>corr</u><u>ect</u><u> </u><u>.</u></h3>
Answer:
$300
Step-by-step explanation:
Let D = Dave's savings and S = Sam's savings.
(1) D/S = 5/4
(2) (D – 40)/(S-40) = 13/10 Multiply (1) by 4S
(3) 4D = 5S Multiply (2) by 10(S-40)
10(D - 40) = 13(S - 40) Remove parentheses
(4) 10D – 400 = 13S - 520 Solve (3) for S
S = (4/5)D Substitute into (4)
10D – 400 = 13(4/5)D - 520 Multiply each side by 5
50D – 2000 = 52D – 2600 Subtract 50D from each side
-2000 = 2D – 2600 Add 2600 to each side
600 = 2D Divide each side by 2
D = $300
Dave's savings at first were $300.