Answer:
x=5, y=8
Step-by-step explanation:
x+y=13
2x-y=2
add these two equations
3x=15
therefore x=5
apply this value in x+y=13
5+y=13
then y=13-5 = 8
Answer:
45
23
104
49
Step-by-step explanation:
The answer is C because -2 is less than or equal to 5. (4 times 0 is 0)
Answer:
and 
Step-by-step explanation:
The equation of the isotope decay is:

14-Carbon has a half-life of 5568 years, the time constant of the isotope is:


The decay time is:
(There is no a year 0 in chronology).

Lastly, the relative amount is estimated by direct substitution:




