At a particular music store, cds are on sale at $12.00 for the first one purchased and $9.00 for each additional disc purchased. maria spends $84.00 on cds. how many cds has maria purchased ?
a- 6
b- 7
c- 8
d-9

David and alton are training for a race. they spend 35 minutes stretching and then go on a 5 mile practice run. david runs at a pace of 7 min/mile. alton runs at a pace of 8 min/mile. write an equation for each runner that shows the total length of their workout. then solve each equation showing your work