$...1\mathrm{.}17$ As part of a study for the Department of Labor Statistics, Shakira Dominguez has been assigned the task of evaluating the improvement in productivity of small businesses. Data for one of the small businesses she is to evaluate are shown in the table. The data are the monthly average of last year and the monthly average this year. Determine the multifactor productivity with dollars as the common denominator for:

a$.$ Last year.

b$.$ This year.

c$.$ Then determine the percentage change in productivity for the monthly average last year versus the monthly average this year on a multifactor basis.