Five workers have been hired to complete a job. If one additional worker is hired, they could complete the job $15$ days earlier. If the job needs to be completed $40$ days earlier, how many additional workers should be hired?
Let x be the days to complete the job in the first case
The amount of work to be done is number of workers * numer of days = 5x
So....in the second case
5x = 6 ( x -15)
5x = 6x - 90
90 = x = the number of days to complete the job in the frst scenario
So
5 * 90 = n (90 - 40) where n is the toal number of workers needed in the last case
450 = 50n
450 / 50 = n = 9
So.... 9 - 5 = 4 additional workers should be hired