Two tailors, Danielle and Tammy, sit down to do some embroidery. Danielle can embroider 6 shirts per hour, and Tammy can get through 4 shirts per hour. In addition, the tailors had previously finished some shirts. Danielle has already completed 9 shirts, and Tammy has completed 11 shirts. Danielle and Tammy decide to take a break when they have finished the same total number of shirts. How many shirts, in total, will each tailor have finished? How long will that take?