b) The demand for chicken is given as follows:
\[
\mathrm{Q}_{2}=8.300+5 \mathrm{P}_{1}-2,5 \mathrm{P}_{2}+0,2 \mathrm{Y}
\]
Where \( \mathrm{P}_{1} \) denotes the price of beef, \( \mathrm{P}_{2} \) denotes the price of chicken and Y denotes the mean income. If the price of chicken increases by \( 20 \% \), by what percentage will the demand for chicken change, given that \( \mathrm{Y}=10.000, \mathrm{P}_{1}=210 \) and \( \mathrm{P}_{2}=85 \).