the weight of the substance after 28 years is 8 grams.
<h3>How to determine the amount</h3>
We have that the half life of a substance is defined as the time required for the substance to decrease by half
The formula for calculating the half - life of a material is given as;

Where
- N(t) is final amount
- No is the initial amount = 128 grams
- t1/2 is the half life = 7 years
- t is the time elapsed = 28 years
Substitute into the formula
N(t) = 128 × (0. 5) ^28/ 7
N (t) = 128 × ( 0. 5) ^ 4
N(t) = 128 × 0. 0625
N(t) = 8 grams
Thus, the weight of the substance after 28 years is 8 grams.
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Answer:
Plan B
Step-by-step explanation:
Let's calculate the amount required for each plan
<h3>Plan A</h3>
- 0.15*200 + 0.10*100 = $40
<h3>Plan B</h3>
- 15 + 200*0.05 + 100*0.05 = $30
As we see Plan B costs less
Answer:

Step-by-step explanation:
Equation: 
1).
→
2).
∴ 
3). 

4). now plug
into 


5). Minimum (0,-5) ∴ 
Answer:
The answer would be x=13.5
Step-by-step explanation: 13.5 times 2 equals 27. 27 plus 2 equals 29.
<u>Let's consider the facts at hand</u>:
- By Vertical Angle Theorem ⇒ ∠BCE = ∠DCF
- ∠BEC = ∠DFC
- Sides BE = DF
<u>Based on the diagram, triangles BCE and triangles DCF are similar</u>
⇒ based on the Angle-Angle theorem
⇒ since ∠BCE = ∠DCF and ∠BEC = ∠DFC
⇒ the two triangles are similar
Hope that helps!
<em>Definitions of Theorem I used:</em>
- <u><em>Vertical Angle Theorem: </em></u><em>opposite angles of two intersecting lines must be equal</em>
- <u><em>Angle-Angle Theorem:</em></u><em> if two angles of both triangles are equal, then the given triangles must be similar</em>
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