Definition: You are provided with an arithmetic question. Your task is to compute the solution using the given arithmetic operations. The only arithmetic operators needed to answer the questions are'+'(addition) and'-'(subtraction). The answer should be correct to one decimal place.
Input: On her vacation last summer, Trisha walked all over New York City to buy souvenirs. First, she walked 0.12 mile from her hotel to a postcard shop. Then she walked 0.15 milefrom the postcard shop to a T-shirt shop and 0.63 mile from the T-shirt shop back to the hotel. How many miles didTrisha walk in all?

0.9