This problem is about percentages.
We know that Jack's health plan decreased from $325 to $115.
To find the percentage that represents this decreased, we just need to divide the least numbers by the greater number
![(115)/(325)=0.35](https://img.qammunity.org/2023/formulas/mathematics/college/f7m1g6nd8pbr316hg0h468h3bm2ez3k2eu.png)
Then, we multiply this result by 100, to get it in percentage
![0.35\cdot100=35](https://img.qammunity.org/2023/formulas/mathematics/college/3vjyfm08k0bs3hewa8bm7mc3dwf0lmhhul.png)
Therefore, the right answer is 35%.