Given a point and a plane, how do you find a line that is parallel to the plane that passes through the point?

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?

On a string instrument, the length of a string varies inversely as the frequency of its vibrations. an 11-inch string has a frequency of 400 cylces per second. find the frequency of a 10-icnch string.

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