iris has 120 songs on her playlist each week she downloads 4 new songs. write an expression to show the total number of songs on iris's playlist after W weeks.
The function has a base constant of 120 songs. Then for each week, 4 songs are added. On week 1, w=1, and thus it is 120+1(4). On week 2, w=2, and thus it is 120+2(4).