The Total Weekly Sales for a Newly Released Portable Media $$\left\{ \begin{array} { l l } S = 10 x + 70 & \text { PMP1 } \\S = - 10 x + 210 & \text { PMP2 }\end{array} \right.$$

Multiple Choice

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 approximate the total weekly sales S (in thousands of units) for each PMP are $$\left\{ \begin{array} { l l } S = 10 x + 70 & \text { PMP1 } \\S = - 10 x + 210 & \text { PMP2 }\end{array} \right.$$ where 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.After how many weeks will the sales for the two PMPs be equal

A) 11 weeks
B) 9 weeks
C) 7 weeks
D) 3 weeks
E) 5 weeks