Maria wants to buy a trophy and engrave her son's name on it. At Trophies Unlimited, trophies cost $12 each and engraving costs 40€ per letter, while at Centerpiece Trophies, trophies are $12.50 each and engraving is 30c per letter. If Maria's costs would be the same at both stores, which equation shows the number of letters, x, in her son's name?