What fraction and whole number does the model represent

Empty box + box + empty box fill in the box is equal to 30 how

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.

Which function represents the sequence? f(n)=n+3 f(n)=7n−4 f(n)=3n+7 f(n)=n+7