Help please, my brains is empty :o(

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.

Kelli swam upstream for some distance in a hour. she then swam downstream the same river for the same distance in only 6 minutes. if the river flows at 5km/hr, how fast can kelli swim in still water?

Solve the system of equations. 2x-2y=-4 and x+y=8. show work