Which expression is equivilent to 1/5 (150x80y+50-50x-25y+20)

Vinay constructed this spinner based on the population of teachers at his school according to vinays model what is the probability that he will have a male history teacher two years in a row

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

Marcus and cody both leave the park at the same time, but in opposite directions. if cody travels 6 mph faster than marcus and after 4 hours they are 64 miles apart, how fast is each traveling? solve using rare times time = distance.