Answer:
The equation is: 
Step-by-step explanation:
Caroline was thinking of a number.
We are going to call this number x.
Caroline halves the number and gets 7.3.
To find half of a number, we multiply by 1/2. So


The formula for this is

. Filling in accordingly,

. This simplifies to

and 36=6x. Therefore, x = 6 so the bases are 6 and 12.
33•3 is 99, so the answer is 3