12. Make equation and plug in
13. Proportion
14. Finding a constant rate, and then manipulate
12. Where x is miles driven, and y is answer, and z is days
19.95z+0.15x=y
Plug in two values
19.95 x 2 + 0.15 x 250 = y
39.93+37.5 = y
y=77.43
13. 5:2 as 175:x
5/2 = 175/x
x = 70
70+175=245
14. 260:5 = x:1
260/5=x/1
x = 52
52:1 = y:9
52/1 = y/9
y = 468
I hope you understand the process.
Answer: 231
<u>Explanation:</u>
Liwen Celina
5x 6x
5x - 21 = 
6x
5x - 21 = 4x
<u>-4x +21</u> <u>-4x +21 </u>
x = 21
Liwen: 5x = 5(21) = 105
Celina: 6x = 6(21) =<u> 126</u>
Total: 231
The bones at the time they were discovered when the radioactive element carbon-14 has a half-life of total 5750 years are 10062.5-year-old.
<h3>What is half-lives?</h3>
Half lives is the time interval which is need to decay the atomic nuclei of a radioactive sample.
There is a scientist who determined that the bones from a mastodon had lost 70.3% of their carbon-14. Thus, the fraction remaining is,
f=1-(70.3/100)=1-0.703
f=1-(70.3/100)=0.297
Now the fraction remaining can be given as,
f=(1/2)ⁿ
Here, n is the half life elapsed. Put the value of fraction remaining.
0.297=(1/2)ⁿ
n=1.75
The radioactive element carbon-14 has a half-life of total 5750 years. Thus,
Years=1.75*5750
Years=10062.5
Thus, the bones at the time they were discovered when the radioactive element carbon-14 has a half-life of total 5750 years are 10062.5-year-old.
Learn more about the half lives here;
brainly.com/question/2320811
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Answer:
a=-8/5
Step-by-step explanation:
(-1/2a-5)=3a+1
To find the opposite of 1/2 a−5, find the opposite of each term.
-1/2a-(-5)= -3a+1
The opposite of −5 is 5.
-1/2a+5=-3a+1
add 3a to both sides
-1/2a+5+3a=1
Combine-1/2and 3a to get 5/2a
5/2a+5=1
Subtract 5 from both side
5/2a=1-5
Subtract 5 from 1 to get −4.
5/2a=-4
Multiply both sides by 2/5 =0.4, the reciprocal of 5/2=2.5.
a=-4x(2/5)
express -4x(2/5)=1.6 as single fraction.
a= -4x2/5
Multiply −4 and 2 to get −8.
a=-8/5
Fraction −8/5 ≈−1.6 can be rewritten as −8/5 =−1.6 by extracting the negative sign.
a=-8/5
