Problem regarding bacteria increase modeled by formula Studying "Basic Mathematics" p.358, by Serge Lang, came across this exercise. 

I don't know how to start with it. Any insight would be appreciated.

Hint:
First note that $C=B(0)=10^6$.
Next, you can rewrite this equation as $\;\dfrac{B(t)}{B(0)}=\mathrm e^{kt}$, and you have to find $k$. You're given that
$$\frac{B(12)}{B(0)}=2. $$
WWhen ytou have $k$, you'll just have to solve
$$\frac{B(t)}{B(0)}=10.$$
Can you end the calculations?
