At the end of a snow storm, Caroline saw there was a lot of snow on her front lawn. The temperature increased and the snow began to melt at a steady rate. The depth of snow on Caroline's lawn, in inches, can be modeled by the function S(t)=-0.75t+15,S(t)=−0.75t+15, where tt is the time, in hours, after the snow stopped falling. What is the slope of the function and what is its interpretation in the context of the problem?