How do I know if an equation is linear and a function?

ex.
7y - 8 = 20

Gretchen is setting up for a banquet. she has 300 chairs and needs to distribute them evenly among t tables. how many chairs should she put at each table? write your answer as an expression.

Someone answer this asap for the function f(x) and g(x) are both quadratic functions. f(x) = x² + 2x + 5 g(x) = x² + 2x - 1 which statement best describes the graph of g(x) compared to the graph of f(x)? a. the graph of g(x) is the graph of f(x) shifted down 1 units. b. the graph of g(x) is the graph of f(x) shifted down 6 units. c. the graph of g(x) is the graph of f(x) shifted to the right 1 unit. d. the graph of g(x) is the graph of f(x) shifted tothe right 6 units.

Atruck can be rented from company a $50 a day plus $0.60 per mile. company b charges $20 a day plus $0.80 per mile to rent the same truck. find the number of miles in a day at which the rental costs for company a and company b are the same