Answer:
Step-by-step explanation:
Cross multiply on both sides
= (x + 1) (21) = 15(x + 3)
= 21x + 21 = 15x + 45
Bringing like terms on one side
21x - 15x = 45 - 21
= 6x = 24
x = 24/6 = 4
Option A is the correct answer
The mass of cesium left afer 120 years if the original mass of cesium is 8640 with an half-life of 30 years, is 540 grams.
<h3>What is half-life?</h3>
This can be defined as the time taken for half the amount of a radioactive substance to decay.
To calculate the amount of cesium left after 120 years, we use the formua below.
Formula:
- R' = R/(
)............. Equation 1
Where:
- R = Original amount of Cesium
- R' = New amount of cesium
- T = Total time
- t = Half-life
From the question,
Given:
- R = 8640
- T = 120 years
- t = 30 years
Substitute these values into equation 1
- R' = 8640/(
) - R' = 8640/

- R' = 8640/16
- R' = 540 grams.
Hence, The mass of cesium left afer 120 years is 540 grams.
Learn more about half-life here: brainly.com/question/25750315
Answer:
here u go
Step-by-step explanation:
< DBC (angle DBC)
Answer: 17/60
Step-by-step explanation:
Change all of the fractions to have a common denominator:
LCM of 10, 12, 15 is 60
You get 12/60, 25/60, and 54/60.
54/60 is what he had at the start, and so you can just subtract what he gave away
54/60-12/60=42/60
42/60-25/60=17/60
17 is a prime number so you cannot simplify the fraction
Select all the correct locations on the graph. At which points are the equations y = x2 + 3x + 2 and y = 2x + 3 approximately equal? 2.