If you were charged $1152 in taxes on a $2560 purchase. What percent tax were you charged

The card shoppe needs to maintain 21 percent of its sales in net working capital. currently, the store is considering a four-year project that will increase sales from its current level of $349,000 to $408,000 the first year and to $414,000 a year for the following three years of the project. what amount should be included in the project analysis for net working capital in year 4 of the project?