Using the correct answer can somebody explaine me how this problem is solved: Based on Taguchi approach determine the $S{N}_{av}$ ratio of the optimum level for factor $B$

according to the data below:

The correct answer MUST be written with decimal POINT $(1\mathrm{.}23).$ The value $1,23$ is wrong!!!.

Round the calculations to the $2$ digit after the decimal point.

Answer:

The correct answer is: $23\mathrm{.}90$svssssss