The formula is
A=p e^rt
A future value (triple amount)=3p
P present value=p
E constant
R interest rate=0.12
T time =?
Plug in the formula
3p=p e^(0.12t)
3=e^(0.12t)
Solve for t
Take log for both sides
Log (3)=0.12t×log (e)
Divide both sides by log (e)
0.12t=log (3)÷log (e)
Divide both sides by 0.12
T=(log(3)÷log(e))÷0.12
T=9.1551 years round your answer to get 9 years
Hope it helps!
