20 points Determine whether Y varies directly with X if so find the constant of variation and write the equation

Triangle xyz has vertices x(1,3), y(0,0)

Tod does not have any cookies. david gives jeff 8 cookies. then he splits half of the cookies he has left with tod. david let’s c represent the number of cookies that he starts with. he finds the number of cookies that tod has is 1/2 the difference of c and 8. write an expression to represent the number of cookies that tod has.

Check all that apply. f is a function. f is a one-to-one function. c is a function. c is a one-to-one function.