Using SPSS, which test do I run to find the answer: I have two columns of variables, one a provider type (private code 0, public code 1) and a column of costs. How do I conduct a difference of means test?

The actual question: "The Department of Service Financing in Belmont, NY has been experimenting with having city units provide services in-house vs having private contractors provide the same services. In the city grounds department, half of the landscaping work is performed by city crews, whereas the other half is performed by private landscaping firms. The city manager has collected 125 random samples of weekly expense report data for both city and private providers. He asks you to conduct a difference of means test. What can the city manager conclude about the difference between in-house and private service costs?"