To double the principle the formula is
2p=p e^rt
2=e^rt
2=e^0.12t
Solve for t
T=(log(2)÷log(e))÷0.12
T=5.78 years
take 16+5=21. 29-21=8 so answer is 8
A proper fraction is a fraction less than one, with the numerator less than the denominator so 1/2 is your answer