Samantha found a great deal on sweatshirts at the mall and bought 5 sweatshirts at the
Super Duper sale price. Allison went the next day, but the sale was over, so she only bought
2 sweatshirts and paid $30 more per sweatshirt than Samantha. If the total cost of all 7
sweatshirts was $340, how much did one sweatshirt cost at the Super Duper sale price?