A correct and simple way to solve this problem is:
$ \require{cancel}100 \cancel{\text{ Q2 euros}} \cdot \frac{95 {\text{ Q3 euros}}}{97.5 \cancel{\text{ Q2 euros}}} = 97.44 \text{ Q3 euros} $
We need to change units from units of Q2 euros to units of Q3 euros. This is like any change of units (eg. from feet to inches). For food, 95 euros in the 3rd quarter is equivalent to 97.5 euros in the 2nd quarter. Multiplying by the conversion factor $\frac{95 {\text{ Q3 euros}}}{97.5 \text{ Q2 euros}}$ is like multiplying by 1. For example:
$ \require{cancel}2 \cancel{\text{ feet}} \cdot \frac{12 {\text{ inches}}}{1 \cancel{\text{ feet}}} = 24 \text{ inches} $
This is an easy, less error prone way to change units.
Difference with the accepted answer
The accepted answer isn't quite precise. It says the percent increase from Q2 to Q3 is 1 minus the percent increase from Q3 to Q2:
$ \frac{X_3 - X_2}{X_2} \approx 1 - \frac{X_2 - X_3}{X_3}$
That's not a bad approximation for $X_2 \approx X_3$ but it's not quite right.