We know that the year has 52 weeks
From 5 weeks, you work 4. So, we can use the rule of three
Number of weeks Weeks of work
5 4
52 x
[tex]\begin{gathered} 5x=4\cdot52 \\ 5x=208 \\ x=\frac{208}{5} \\ x=41.6\text{ w}eeks \\ or\text{ 41 complete w}eeks\text{ } \end{gathered}[/tex]