To find out how many weeks Timmy needs to work to earn $183.83, you can divide the total amount he wants to earn by the amount he earns per week.
So, the calculation will be:
\[ \text{Number of weeks} = \frac{183.83}{20} \]
Calculating that gives:
\[ \text{Number of weeks} = 9.1915 \]
Since Timmy cannot work a fraction of a week, we'll round up to the next whole number. Therefore, Timmy will need 10 weeks to earn at least $183.83.