Hi,
*Note, whenever possible, use one variable in the set up
Let x represent number of Sear's iPods,
then 8x would be the number of the Best Buy iPods
Write as we Read***
8x -x = 490
7x = 490
x = 70, the number of Sear's iPods sold. Best Buy sells 560 (8*70)
checking our answer
560 - 70 = 490