How do you represent any number in an equation?

Shania's test scores in 8 subjects were 88, 91, 85, 74, 69, 72, 80, and 87. shania found the middle number of her scores. which type of measure did she find?

Someone this asap for a group of students attends a basketball game. * the group buys x hot dogs at the concession stand for $2 each. * the group buys y drinks at the concession stand for $3 each. the group buys 29 items at the concession stand for a total of $70. how many hot dogs did the group buy?

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