answer: the ksp expression for the system
the od the substance that solubility product is defined as mathematical product of concentration of dissolved ions raised to the power equal to their stoichiometric coefficient in reaction.
for the given system:
the ksp expression for the system :
your answer is going to be 14.54. 16.99 off of 7% sales tax is $18.18, but 20% off is $14.54.