The correct answer is the second option: plus or minus square root of 20
Hope this helped :)

Taking natural logs of both sides, we get
0.015t=ln 3
t = ln 3/0.015 = 73.24
The answer is 73.24 years.
-9 is a negative number, so plus 25, it would be 16. The minus sign and the negative sign of -10 cancel out, so it is plus 10, ending up with 26. Finally, the + and - becomes negative (positive times negative equals negative), so it is -6 and you’ll end up with a final answer of 20.
I'm pretty sure the answer is -3