Mark want's to buy a new smart phone. He finds four stores selling the smart phone he wants. The deals at the store are shown.
Store A: 20% off a $1000 price
Store B: 25% off of an $850 price
Store C: $900 price with a $150 rebate
Store D: $800 price with a coupon for $200 off
At which store should Mark buy his New Smart Phone?