Also need help with this one !

How do you determine whether a relationship represented as as graph is linear or nonlinear

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.

Find the zeros of each function. f(x) = 6x^2 - 7x - 20