I need help solving this problem 8th grade

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.

What is the value of 4x to the third +4x if x is 4

What is the 8th term of the geometric sequence with this explicit formula? an= )(n-1)