500 shirts / 3 hours = 166 2/3 shirts per hour.
Divide total shirts by shirts per hour:
1800 / 166 2/3 = 10.8 hours.
Look up "Everything You Need To Know About Math In One Big Fat Notebook pdf." It's the best thing I've ever been given, I have it with me in math class all the time and I've aced every test. I have it with me right now and it has everything I've ever been taught about math in it so it might help you.
The absolute value of -81 has the same absolute value as that of 81 because they both have the same distance to 0.
