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:





Answer:
QM = 21
Step-by-step explanation:
The diagonals of a parallelogram bisect each other, then
QM = PQ = 21
X - invested for the money at 11%
70 000 - x - deposited at 12%
0.11x + 0.12(70000-x)=7900
0.11x + 8400 - 0.12x = 7900
8400- 7900 = 0.01x
500 = 0.01x
x=50 000 invested at 11%
rest (20K) invested at 12%