Answer:
30%
Explanation:
The level of decay is determined by the number raised to the power.
y = 0.4(0.7)^t
If you had 1^t, there would be no decay or growth since 1^t is always 1.
Instead, you have 0.7^t
As t increases, 07^t decreases. That is where the decay comes from.
Now look at 0.7
In the general decay equation, you have
y = a(1 - r)^t
r is the rate of decay.
Here we have 0.7
0.7 = 1 - 0.3
the rate of decay is 0.3 or 30%