Abraham Lincoln, i've read that story a long time ago myself and I remember who said that.
Answer:
Rate of Decay = 8%
Step-by-step explanation:
The decay formula is:

Where F is the final value (here, it is given as "Y")
P is the initial value (here, given as 20,000)
r is the rate of decay (what we need to find)
t is the time (given as 2)
Comparing both the equations:

We see that:
1 - r =0.92
We solve for "r":
1 - 0.92 = r
0.08 = r
The rate of decay is 0.08, as a percentage, we need to multiply by 100, so we have:
0.08 * 100 = 8%
Rate of Decay = 8%
Answer:
Step-by-step explanation:
3x²-5x+2=0
3x²-3x-2x+2=0
3x(x-1)-2(x-1)=0
(x-1)(3x-2)=0
either x-1=0 which gives x=1
or 3x-2=0
x=2/3
2.5y + 3x = 27
5x - 2.5y = 5
Align the variables to make solving this easier.
2.5y + 3x = 27
-2.5y + 5x = 5
You can see that the 2.5y and -2.5y cancel each other out. Then add the 3x and 5x, and 27 + 5.
3x = 27
5x = 5
8x = 32
Divide both sides by 8.
x = 4
Now input that x into one of the equations to get y.
2.5y + 3(4) = 27
2.5y + 12 = 27
2.5y = 15
y = 6
The answer to this system of equations is x = 4, y = 6. (4, 6)
For this case we must follow the steps below:
step 1:
We place each of the given points on a coordinate axis
Step 2:
We join the AC points (represented by the orange line)
We join the BD points (represented by the blue line)
It is observed that the resulting figure after placing the 4 points on a coordinate axis, turns out to be a rhombus.
In addition, the blue and orange lines turn out to be perpendicular, that is, they have an angle of 90 degrees between them. This can be verified by finding the slopes of each of the two straight lines (blue and orange), which must be opposite reciprocal, that is, they comply: 
In this case, the slope of the orange line is
and that of the blue line is 
Then
, it is verified that they are perpendicular.
Thus, the conclusion is that ABCD is a rhombus and AC is perpendicular to BD.
Answer:
See attached image
Option D