Samuel ordered four dvds each dvd cost $19.99. he has a discount card for 20% the sales tax is 6.75% what is the total cost

Atrucker had a load of grain containing 2 tons. she unloaded 1 ton and 1,200 pounds at the warehouse. how much grain does she still have left on the truck?

Mrs. morton has a special reward system for her class. when all her students behave well, she rewards them by putting 3 marbles into a marble jar. when the jar has 100 or more marbles, the students have a party. right now, the the jar has 24 marbles. how could mrs. morton reward the class in order for the students to have a party?

How do i simply this expression (quadratic formula basis) on a ti-84 or normal calculator?