A store sells mugs. Each mug costs the same amount. During a sale, the store reduces the price of each mug by $1.75. Wen spends $28.20 on 5 mugs at the sale price.
What was the price of 1 mug before the sale?
Let's call the price of one mug before the sale "x".
After the sale, the price of one mug is x - $1.75.
Wen spends $28.20 on 5 mugs, so the equation is 5(x - $1.75) = $28.20.
Solving for x gives 5x - $8.75 = $28.20.
Adding $8.75 to both sides of the equation gives 5x = $37.95.
Dividing both sides of the equation by 5 gives x = $7.59.
Therefore, the price of one mug before the sale was $7.59. Answer: \boxed{7.59}.