\(\left(C_{17}H_{35}COO\right)_3C_3H_5+3NaOH\rightarrow3C_{17}H_{35}COONa+C_3H_5\left(OH\right)_3\\ n_{\left(C_{17}H_{35}COO\right)_3C_3H_5}=\dfrac{8,9}{890}=0,01\left(mol\right)\\ n_{C_{17}H_{35}COONa}=3n_{\left(C_{17}H_{35}COO\right)_3C_3H_5}=0,01.3=0,03\left(mol\right)\\ \Rightarrow m_{C_{17}H_{35}COONa}=0,03.306=9,18\left(kg\right)\\ \Rightarrow m_{xp}=\dfrac{9,18}{60\%}=15,3\left(kg\right)\)