Complete the problem to represent the situation given by the equation 0.40e + 10 + 15 = 0.20e + 5 + 25. At one store a trophy costs $15, initial engraving set-up cost $0.40 , and engraving costs $0.20 per letter. At another store, the same trophy costs $25 , initial engraving set-up costs $5, and engraving costs $10 per letter. How many letters, e, must be engraved for the costs to be the same?