Answer:D
Step-by-step explanation:
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
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Answer:
Yes
Step-by-step explanation:
Let's solve for x.
5x+15y=12
Step 1: Add -15y to both sides.
5x+15y+−15y=12+−15y
5x=−15y+12
Step 2: Divide both sides by 5.
5x
5
=
−15y+12
5
x=−3y+
12
5
Answer:
x=−3y+12/5
Let's solve for y.
5x+15y=12
Step 1: Add -5x to both sides.
5x+15y+−5x=12+−5x
15y=−5x+12
Step 2: Divide both sides by 15.
15y
15
=
−5x+12
15
y=
−1
3
x+
4
5
Answer:
y=-1/3x+4/5
Hope this helps!
-Josh
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