For part (a) the answer is 400 grams for part (b) 198.63 grams and for part (c) 20 years.
<h3>What is exponential decay?</h3>
During exponential decay, a quantity falls slowly at first before rapidly decreasing. The exponential decay formula is used to calculate population decline and can also be used to calculate half-life.
We have an equation for radioactive decay:

a) Plug t = 0

m(0) = 400 grams
b) plug t = 20 years

After solving:
m(20) = 198.63 grams
c) Plug m(t) = m(0)/2 = 400/2 = 200 grams

x = 19.80 years ≈ 20 years
Thus, for part (a) the answer is 400 grams for part (b) 198.63 grams and for part (c) 20 years.
Learn more about the exponential decay here:
brainly.com/question/14355665
#SPJ1
The answer is d 41 X 12= 492
Step-by-step explanation:
12 (12 + 17)
12(41)
= 492
Well, this is a guess. Jim goes before john, but after joe. So Jim is second. John is third, so that leaved Joe.
Joe, Jim, John. But I don't know about the other 2.
---
sorry if this doesn't help
(9,0) (0,9) choose any two points since it’s a straight line honey and the dk the difference between the two points
9-0
———. = 1
0-9