Find the difference between the 2 numbers which will give you the increase from the lower value to the higher. Divide this increase by the original (lower) number and multiply the result by 100 to get the percentage. For us that looks like this:
![(5.2-3.5)/(3.5) *100](https://img.qammunity.org/2019/formulas/mathematics/high-school/umlklvwfhpk8zbxm441y9hm8zqehjmndhi.png)
. Simplifying a bit we have
![(1.7)/(3.5)*100=48.5%](https://img.qammunity.org/2019/formulas/mathematics/high-school/j70scv8dep6l9zv6fk4d55en5oz1zt8oxy.png)
or 49%, rounded.