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:
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Answer: 8.00
Step-by-step explanation:
1.25a=3 0.50=5 so the answer is D, 8.00
I can’t read the question, what is the question?
Answer:
2x+9y=18
Step-by-step explanation:
Distribute the denominator
y=-2/9x+2
9y=-2x+2
9y+2x=2
im sorry if this is wrong