Answer:
.
Step-by-step explanation:
We are given that
and
(because that's the ground), so substituting that into
gives
.
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%
9m-28=2m
9m-28-2m=2m-2m
(9m-2m)-28=0
7m-28=0
7m-28+28=0+28
7m=28
(7m)/7 = 28/7
m=4
Here is the graphed equation :)