Plz help I can’t understand this at all or know how to do it

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.

In priyas math class there are 10 boys and 15 girls. what is the ratio of boys to girls in priyas math class? express your answer as a decimal

How can you find the mean absolute deviation (mad) for this set of data?