Are Brainy tutors still a thing if not I’m gonna fail algebra

Which of the following is the correct ratio for converting kilograms to grams

Nick has box brads. he uses 4 brads for the first project. nick let’s b represent the original number of brads and finds that for the second project, the number of brads he uses is 8 more than half the difference of b and 4. write an expression to represent the number of brads he uses for the second project.

Bring the fraction a/a-4 to a denominator of 16-a^2