The total weekly sales for a newly released portable mediaplayer (PMP) increased each week. At the same time, the totalweekly sales for another newly released PMP decreased eachweek. Models that approximate the total weekly sales S (inthousands of units) for each PMP are= 10x + 70S = = -10x + 210where x represents the number of weeks each PMP was instores, with x = 0 corresponding to the PMP sales on the dayeach PMP was first released in stores. After how many weekswill the sales for the two PMPs be equal?11 weeks5 weeks3 weeks9 weeksPMP 1PMP27 weeks

The total weekly sales for a newly released portable media player PMP increased each week. At the same time, the total weekly sales for another newly released PMP decreased each week. Models that approximates the total weekly sales S in thousands of units for each PMP areS=10x+70 PMP1S=-10x+210 PMP2where x represents the number of weeks each PMP was in stores, with x=0 corresponding to the PMP sales on the day each PMP was first released in stores.To deteermine the number of weeks after which the two PMPs will be equal.Solution: The models that approximates the total weekly sales S in thousands of units for each PMP are,S=10x+70 PMP1S=-10x+210 PMP2where x represents the number of weeks each PMP was in stores, with x=0, corresponding to the PMP sales on the day each PMP was first released in stores.Now, when the total weekly sales of both PMPs are equal then, we have, 10x+70=-10x+210⇒10x+10x=210-70⇒20x=140⇒x=14020⇒x=7Thus, after 7 weeks, the total weekly sales of both PMPs will be equal.