Answer:
5 letters
Explanation:
Let x = the number of letters engraved.
For the first store, the cost can be written as (18.50 + 0.15x).
For the second store, the cost can be written as (18 + 0.25x).
For the cost and value of x to be the same, let them equal eachother and evaluate x:
18.5 + 0.15x = 18 + 0.25
0.1x = 0.5
∴x=5